1974 full time 4x4 to 4x2 conversion
 

Hi Everyone,
I've looked everywhere for information on this but haven't gotten any help. I have a 1974 K20 3/4 ton with fulltime 4-wheel drive that I need to convert to part-time. It's my daily driver and I only get 11 mpg. I was hoping to bump that up just a little. :help:
I bought the Mile Marker 423 Manual Locking Hubs and the 203 Transfer case kit already. I started on Saturday and to my dismay, found that there are studs, washers and nuts holding on the OEM Hub and not holes and bolts for the Mile Marker hub to bolt on. Does anyone know what I need to do to make this work? Do I need to buy different rotors/hubs or what? Please Help! Thanks!!!:dohh:

Re: 1974 full time 4x4 to 4x2 conversion
 

Can you post a pic of the hub?

Re: 1974 full time 4x4 to 4x2 conversion
 

I'll try a little later. Suffice it to say that instead of bolts threading into the stock hub, there are studs, washers and nuts holding them on. The Mile Marker 423 Hubs have 6 holes that match the rotor hub, but the studs are too short to use the washers and nuts from the stock setup.

Re: 1974 full time 4x4 to 4x2 conversion
 

Wonder if there is a way to replace the studs



Home » 4X4 Locking Hubs » Mile Marker 4X4 Locking Hubs


Product ID: 423
Manufacturer: Mile Marker
Mile Marker #423 Manual Locking Hubs Dana 44 Heavy Duty with 6 Bolt Flange

Mile Marker 4X4 Manual Locking Hubs #423 - Chrome - Fits Heavy Duty Dana 44 axles with external 6 bolt flange. These Hubs fit Chevy, Dodge, International Harvester, Jeep J20 Pickup 1974-1977 (6 Bolt 19 Spline) and Ford 1/2 and 3/4 ton trucks with a Dana 44 HD 19 spline axle and external 6 bolt flange mount.

>> These are the hard to find Heavy Duty hubs that replace worn out Spicer hubs as well as others <<

Re: 1974 full time 4x4 to 4x2 conversion
 

My thoughts Exactly. Those are the hubs: Mile Marker 423's. Here are a couple of pics of the stock hubs showing the washers and nuts.

Re: 1974 full time 4x4 to 4x2 conversion
 

why cant you reuse the nuts/washers on the studs with the MM hubs. Is the flange on the mm hub thicker than the stock flange? From the above pics, It doesn't look much different.

Re: 1974 full time 4x4 to 4x2 conversion
 

The base on the new hubs is thicker. The studs aren't long enough.

Re: 1974 full time 4x4 to 4x2 conversion
 

My '73 has the conversion on it from a PO, the hubs are Warn hubs but I'm pretty sure they removed the studs and used bolts of the proper length. I'll have to look this evening when I get home.

Re: 1974 full time 4x4 to 4x2 conversion
 

You should be fine taking the studs out, and using bolts of the proper length. I believe some Chevy Dana 44's came with bolts holding in the drive flange. Also, Dodge Dana 60's used an external drive flange that was held in place with bolts. Studs are arguable stronger, but on a Dana 44 you're going to break something else before you shear off 6 drive flange/hub bolts. My two cents.

Re: 1974 full time 4x4 to 4x2 conversion
 

Just an update:
First of All, Thanks for all the help everyone! I appreciate it.
I was able to pull the studs and do the mods to the hubs and got the 501 mod done to the NP203 transfer too. Good Stuff, but now I've taken it a step further and swapped the NP203 for an NP208 and attached it to a 700R4...what a PITA! Rebuilt tranny from the local Pick and Pull for 50 bucks(and 600 to rebuild and modify for 4X4), the transfer for 140 bucks and associated TV cable, bracket and crossmember mods...wound up costing me about 1500 :-(
Oh well, now my beast is selectable 4X4 or $X2, AND...it's got an Overdrive Tranny!!! Woo Hoo!
Thaks Again Evryone!

Re: 1974 full time 4x4 to 4x2 conversion
 

Not to burst your bubble, but how much gas could you buy for 1500? What is the overall gain in MPG? Sometimes with old technology and carbs miles per gallon isn't always a win-win situation if you know what I mean. Don't get me wrong, I'm all for fuel savings if the price is right :uhmk:

Re: 1974 full time 4x4 to 4x2 conversion
 

Cool, got any pics of the swap? Bet you are loving that low first gear and OD.
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Re: 1974 full time 4x4 to 4x2 conversion
 

propanemudtruck, I hear ya and it'll probably be a couple of years before I break even on the gas costs, but I love the lower first gear and the fact that I'm not winding it out at 60 mph anymore. I drive about 300-400 miles per week, half on the highway, so the extra gear is nice. even a one mpg increase is a ten percent increase so I guess we'll see. I did weigh the cost quite heavily before I committed to it. I just came into a great deal on the rebuilt tranny and transfer(700 bucks) the labor is what cost me. Unfortunately, my severely sloped driveway was no place for me to do the swap alone, so I had to enlist the help of a mechanic friend and his shop.

MTCK, I didn't get any pics of the swap, but suffice it to say...What a PITA, LoL. we had to mod the crossmember, shorten the driveshaft and change the yoke, plus some other little things like the kick-down cable bracket and transmission line routing.
As I have about 5 grand invested in the truck so far, I'm not too bad off. I don't have any car payments so I can "play" a little, thank God. Momma isn't too worried...yet ;)
Not that I'm posting anything "for sale" but I do have a fully functional NP203 with the 4X2 conversion for anyone needing one and is willing to cover the shipping. I just need to get that heavy beast outta here, LoL.

Re: 1974 full time 4x4 to 4x2 conversion
 

The best kind of rig is one that doesn't owe you anything! What kind of mileage are you getting now? Do you know what your axle ratio is? I have a 700r4 truck that came with a 2.73 rearend which made the OD about useless.
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Re: 1974 full time 4x4 to 4x2 conversion
 

I am running 4:10 axles so the lower 1st gear really helps getting off the line, so to speak, and as for the mileage, I'm going to run a couple of tank fulls and average it out. I'll update when I have the numbers. Maybe it'll help, maybe it won't but I really like the way the truck feels now; firmer shifts with the rebuilt 700R4, Overdrive at 45 MPH drops the RPMs about 700 at 60 MPH which is where half of my driving is.