1959 GMC Fleet - 2wd to 4wd
 

I looked up some conversion post but I did not find anything specific for what I am using. Maybe missed it.

I just put external frame GM power steering (73) using a full size car type pitman arm on my 59 GMC. No complaints, all is well and has disc brakes as well. I now want to convert this truck to 4wd. I had changed the pitman arm sector shaft from 4wd to 2wd. Switching back is not a problem.

The truck will have the minimum 4 inch lift as dictated by changing to the Dana 44 front axle.

1) Can I use the stock 75 4wd pitman arm?

2) Can I use the stock 75 4wd draglink?

3) I know I will be mating 2.5 inch perches to 2 inch spring leafs -- know whats needed - have done before.

If it can be used, the 2wd full size car pitman arm would require enlarging the drag link ball taper hole.

The rest of the conversion would be somewhat straight forward as have done it before on my 67.

I will change from manual to a 700R4 with a np208, raise back 4 inches, other, and adjust driveshafts as necessary. Rear axle has already been changed to a 12 bolt.

Any wisdom/help is appreciated.

Re: 1959 GMC Fleet - 2wd to 4wd
 

I can't answer your questions, but a buddy of mine has a '59 fleet vehicle grill and a '55-59 factory grill guard that I always thought would be perfect on a 4x4.
If you're interested, I can pass his contact info to you.
We're in Georgia, but I'm planning a trip to Ohio to hunt rabbits this fall.

Re: 1959 GMC Fleet - 2wd to 4wd
 

I have the grill but I may still be interested in both. I have a dotter and son n law near Stone Mountain. Sometimes they pick up parts for me. If you want to send a pic to my phone or email let me know. dennislbrooks@roadrunner.com

Re: 1959 GMC Fleet - 2wd to 4wd
 

I was planning a similar swap using a 71 dana 44 under my 3100. My plan was to use all the 4x4 specific stuff from the K10 that axle came out of(steering included) eventually I decided to swap to a blazer frame so I ended up selling all those parts off. It’s been 15 years ago now so I don’t remember specifics but I don’t know why it wouldn’t work? This link may help you out. I kinda wish I had done it this way these days.
http://67-72chevytrucks.com/vboard/s...d.php?t=233305
Great looking truck by the way!

Re: 1959 GMC Fleet - 2wd to 4wd
 

That thread is good and I will be referring to it. I have all that is in pic 1 of that build.

His 4wd steering gear is about 4 inches toward the front more than the setup for the straight axle 2wd. That may be an issue -- may have to move mine.

Will not know till I try it. If you have never done it, changing the pitman arm sector shaft from 2wd to 4wd or vice versa is easy if you have the shafts.


I can move the box if needed - don't want to but may have to. Won't be the first thing I have done more than once.


I can complete the axle install and raise the rear ( and drive) before any trans and t-case addition.
I have to change my dana 44 gearing from 3.07 to 3.73 in some manner. May be something at the Springfield fairground swap meet tomorrow.

Re: 1959 GMC Fleet - 2wd to 4wd
 

This is mine with 2wd pitman arm. May depend on how much the 4wd drag link will adjust shorten.

Re: 1959 GMC Fleet - 2wd to 4wd
 

I did change the 3.07 to 3.73 gears to match the rear. I did have to slightly change the position of the steering gear from 2wd position to a position to allow 4wd pitman arm to clear the frame. And I did change the pitman arm sector shaft back to 4wd.


I relocated the shocks. I am awaiting the odd inside passenger side leaf u bolt before I can raise the hoist.

And I have k10 calipers and hoses on the way.


I did remove the shortest leaf. Maybe I can drop an inch more with truck weight. I really do not want to raise the back 4 inches. 2 inches is closer to what I want. May play with front leafs a little more.

Re: 1959 GMC Fleet - 2wd to 4wd
 

I have to fabricate my front sway bar frame mounting points on the 59 Fleet. I have a 1.25" sway bar from a 1984 K10 along with the correct mounting caps on the leaf springs.


Question:
The suspension with weight rest on the springs, are the frame mount caps at the same level as the leaf cap sway bar bolt mount points?


I looked for pics on the web, my chiltons, and my haynes all had no pics I could use to determine. A pic would be nice with findings.

I know 4wheel retail sites sell front mount drop kits if you raise a stock 4wd. Also a raise kit for dropped 2wd. But I am not sure of the starting point.

And yes I still have to raise the rear 4 inches to level it with the front.

Re: 1959 GMC Fleet - 2wd to 4wd
 

I can take pictures in a little bit of the factory Sway bar setup on my 3100(it’s on an 88 blazer frame).

Re: 1959 GMC Fleet - 2wd to 4wd
 

I did get the 4 inch rear lift completed but the front is still an inch or better too high. I know that OrrieG used air bags also on the rear. I want the truck lower not higher. When I put the gm 10 bolt diff/axle in the front I removed the bottom 12 inch leaf. Not sure it made much difference. I have 5 leaves left - 2 inch. I am going to remove the next bottom which is probably 18 inches.

I like level 4wd's. I will get a pic after I bleed the front brakes.

Re: 1959 GMC Fleet - 2wd to 4wd
 

Not a 4wd yet but halfway there. I removed the 2nd spring from the bottom of the oem 6 pack and it dropped the front 1 inch. That is about all you want if you want enough suspension movement in front. I added a snubber above the pumpkin for a little insurance of a soft touch if it ever happens. The back has a 4 inch lift block added to the oem spring pack. This is not even close to a rock crawler setup. I did not get it my correct the first try.

The front sway bar mount has very little guessing as it pretty well has about only 1 mount point height on the frame to not interfere with springs. I need some 1/4" plate to make the mounting bracket.

The front measuring thru the center of the wheel to the top of the front fender cutout is 37". The rear is 34 1/2". I suspect this is a little shorter than a NAPCO.

Power steering is working fine. I am still road testing the ride.

Re: 1959 GMC Fleet - 2wd to 4wd
 

I am ready to pull the T10 and replace with a 350 TH and NP208. I did pull the stock modified steering column and installed an auto tilt steering column. It was less expensive to get an auto tilt than to get an auto floor shifter -- plus I get the tilt and better turn signal features. I was surprised the 59 wheel and horn fit and function - not sure on the canceling cam functioning working yet. Don't ask yet about any rear engine crossmember interference.

I suspect near the end it will be modified with a piece of casing (square or round) as it is a support for the rear front leaf spring hangers even tho I do not use it to support the trans or engine.--- have not got that far yet. In truck/frame modification may be difficult -- I do not want to remove to modify but may be the case.

I was told of a 55-59 napco setting in a barn close around here. I may make an effort to just go see it and get some pics.

I am changing the tilt, turn, and flasher knobs to black ends like a 67. Fortunately the shifter arm is chromed steel as I had to bend it for more dash clearance. I used a torch flame and did little noticeable damage to the chrome. I may sandblast the end of it to make it black with something.

I know this build is nothing new or spectaular but sometimes I receive some good ideas from you guys that fit my budget.

I am making a trip to Atlanta towards the end of October and can pull the 18 foot car hauler behind the K2500 if needed or other.

Re: 1959 GMC Fleet - 2wd to 4wd
 

That column looks great in there. I really do like the “theme” if you will of your truck. This thread is a good motivator for me to get my butt in gear on my 3100. I’ve got a turbo400/np205, front Dana 60 and rear disk brake 14 bolt to swap into it.

Re: 1959 GMC Fleet - 2wd to 4wd
 

I used a 32" column if anyone wants to know. For a smaller shallower steering wheel than the stock one, I might get a 33". That measures from the bottom end of the double D to the top of the upper most housing cup.

Some of this is dependent on the power steering gear placement which also depends on the proper angularity of the pitman arm to the steering arm with full weight on tires.

The wires coming out the middle of the column somewhat limit the tube position if you want the wires exiting below the dash mount but it worked out fine for me.

All my measurements say I can hang the 350TH in there --- I will be lucky to do it with no changes. Then I have to hang the NP208 and see what I have. Transmission must be serviceable once in and of course the torque converter must be accessed to connect to the flexplate.

Had to stop as I had to order flex plate bolts.

Re: 1959 GMC Fleet - 2wd to 4wd
 

My 67 k10 does not have the bellhousing mount support in the location of the rear leaf hangers. I saw it mentioned in a thread or 2 but has anyone removed that bellhousing mount and then just added a rear transmission and/or transfer case support instead?

Re: 1959 GMC Fleet - 2wd to 4wd
 

If your talking about the frame mounts on the bell housing, that is a 2 wheel drive thing. 67-72 Factory 4x4 trucks didn’t get the bell housing frame mounts.

Re: 1959 GMC Fleet - 2wd to 4wd
 

OK, the link where the guy put a np203 in his 59 -- put engine, trans, and transfer case on a bare frame then set the cab on it. I do not know if he could remove the trans from the finished truck without removing the bellhousing cross member.

I removed mine - had to. The cab mounts still hold the frame at that point and I left the riveted sections in for original strength. It is now like my 67 in that area. Now it also has the trans/transfer case mount and crossmember.

Rear driveshaft will be around 42.5 inches. I have not made the final measurement yet.

Re: 1959 GMC Fleet - 2wd to 4wd
 

Subscribed!

Re: 1959 GMC Fleet - 2wd to 4wd
 

I have the speedometer hooked up to the transfer case, it works, but way off. The drive gear is blue - 18 tooth -- and the driven gear is 36. The transfer case must have been under a truck with a 3.42 or 3.23 gear.

I get my speedo gears from LASpeedometer and Gear and the best we can do with that drive gear - 18 - is a 45 driven gear/w housing. Will be close -- just not quite there unless I can get a true 31 diameter tire. My 31x1050's are a little less than 30" now. I run 3.73 gears. Or put a set of 32's on it. Then need more money and maybe engine. 8-)

If I ever have reason to split the transfer case again I will change the blue 18 to a tan 15 then I can run a 36, 37, 38, or 39 for a more accurate speed.

Anyone know how to get the tail housing off the np208 while in the truck??? I think it needs to be removed then split and the tail housing tapped out from the inside.

Re: 1959 GMC Fleet - 2wd to 4wd
 

I fabricated my transfer case shifter mount (3x3x3/16 angle) onto the coupling of the trans and transfer case adapter studs. The shifter is not attached to the body at all like my 67 . I used the shifter from an 86 Ford 250 which has the correct pattern for a right side mount. The pivot is an Nissan upper a-arm mount drilled out to 7/16" then top and bottom mounts attached. I have a little more trimming on the tunnel cover and also remove the mount for sandblasting and painting.

I am not sure how/if I can do it yet but I would rather not put a boot on it and try to go with something like on a 46 chevy truck emergency brake foam slide gasket. dunno

Shifter is in 2 HI position.

Re: 1959 GMC Fleet - 2wd to 4wd
 

Im in to see the rest of this one .

Re: 1959 GMC Fleet - 2wd to 4wd
 

Couple more pics.

Re: 1959 GMC Fleet - 2wd to 4wd
 

I found a suitable transfer case shifter boot for the np208 straight pattern, The footprint was small as I was looking for --- 8.5" x 4" - bottom is flat.

Jeep CJ5/7 Dana 20 p/n 5353263

I got this one on ebay from Barney's Jeep Parts - Waverly, Ohio.


To complete the 4wd, I just need a front driveshaft -- about $250 new -- or maybe at a swap meet. A 77-80 K10/K20 may work.

Re: 1959 GMC Fleet - 2wd to 4wd
 

I have made some body progress. Interior with seats are a satin black, beige textured dash, beige headliner, and will be beige/saddle carpet. Inside door panels are beige exactly matching cab top, dash, and headliner. Steering wheel will be black-- needs a little body work. I can now also place the new windshield and back glass. Also got my first covid shot if that tells you about how old I am. 8-)

Re: 1959 GMC Fleet - 2wd to 4wd
 

Looks awesome!