55.2-59 57 & 59 projects

[78classic]

So I'm new to this era of Chevy pickup and will be looking for advice as I start on the 57 1st. It's running \ stopping right now propelled by a 235 6 cylinder and 4 speed transmission. My first step will be drive train work and want to start with the rear diff. I have access to several 67-72 parts and 73-87 parts from my past work. The best I can tell is the Dana 44 rear I have sitting under the 67 GMC parts truck will be a good swap for the rear diff? Opinions?

[1project2many]

Damn... I miss MT.

Hmm... Why do you want to change the rear? The Dana isn't a bad choice but if the gear ratio is close the the '57 ratio, what are you gaining?

[78classic]

I considered that...I havn't checked the ratio on the 44 yet but my 68 has a 44 with 3.42. I was thinking brake shoes, cylinders, hardware would be easier to come by with a little more modern rear diff?

I probably should plug my numbers in to a calculator, as the plan is to use a turbo 350 and a SBC 350\383 or 400.

[mr48chev]

68 is real close to the same width as the TF but you still the coil spring brackets to deal with.

This snagged from a rear end swap article. I don't know how accurate it is but do know that 70 rear axles are somewhat wider than 66 rear axles. I sold a guy a 70 3.7 Posi for his 66 stepside and the tires barely fit inside the fenders but he did have fatter than stock tires.

It comes down to the if you want to spend the time to clean the rear axle housing up to be able to use it.

[dsraven]

hey, welcome to the forum. nice looking set of trucks you have there. I wish mine looked that good when I dragged them home.
just so you know, the 57 and 59 look like most things will swap between the 2. well, a lot of stuff will but the front sheet metal is obviously different due to the number of headlights. it is also different in length from the firewall forward. the frame is longer out front as well. drivetrain etc will likely all work as well as springs. the frame is longer ahead of the front springs. rad support brackets are located in a different spot as well. the cabs are the same but the later cabs usually have a little dimple in the inner cowl behind the fenders ahead of the doors, it is because the 58-59 front fenders were a little closer to the cowl, on average, than the 55-57 models.
check the assembly manual in the link for frame drawings, track width etc.

https://www.trifive.com/55-59Assy.pdf

http://chevy.oldcarmanualproject.com...esto/index.htm

just as a note for you, before you start. these trucks have a grille ahead of the windshield that directs air into the cab through the cowls and kick panel vents inside the truck. the bottom of the cowls have a small drain area at the bottom (behind the fenders) which may or may not have a small sheet metal piece attached to partially obscure the hole. over time, and depending on where the truck lived over the years, the pine needles or tree leaves would get into the grille, down inside the cowls and plug the drain hole up. another thing that could happen is the drain would plug with ice or simply dirt collected. when the drains plug melted snow or rain will build up inside the cowls and when it gets high enough the water has no choice but to drain out onto the floor of the truck through the kick panel vents. over time the sitting water tends to rot the floor under the pedals, the hinge pillars on the lower sections and also the forward cab mounts spot welded to the underside of the floor. if you look inside the cab and the floor looks like it is not quite level or flat in the front area then your cab mounts are likely rotted out so the weight of the front part of the cab pressing down has caused the floor to bend and sag the area. before you start a rebuild it is a great idea to put the truck(s) up on blocks and do a front to rear check on the whole thing. look closely at those areas. rear cab corners-inner and outer. steps and rocker areas, the rain gutter is another spot that some find rotted after they have spent countless hours on the bottom section first. the area just above the windshield is prone to rot as well as the lower corners of the windshield in the "knee knocker" area. mine had a mouse condo inside the eybrow area above the windshield which held moisture and rotted the roof eyebrow from the inside. if you go around the rain gutter and push with your thumb, above the gutter as you go, you should soon find out if there are soft spots to deal with or not. while you're at it go around the rear window too. the rear cab mount is also prone to rot because it is, again, a sandwiched part that collects dirt and holds moisture. check the assembly manual for a diagram of how it is assembled and you will see what I mean. the doors have inner bracing that is prone to cracking or breaking the spot welds. if you open the door and give a twisting action you will soon see if the door is still solid or not.
not trying to discourage you in any way, just giving you some insight so you go into your project with some knowledge of what to look for.
post up some more pics of your project(s), we would likely all want to see what you have found. what is your plan for the truck(s)? stock? custom? full bore teardown? drive while you work on it slowly? if planning a rework of things under the hood just know the 58-59 is a bit longer in the hood area so a bit more room for water pump to radiator clearance. I also think the fenders are a little wider in the wheel openings as well in case you plan to drop the truck and put some fatties under it. maybe not, a measure of the two would prove it.
front fenders are same for 55-56, 57 is it's own year. 58-59 are same I think. badging on the fenders may have changed from year to year to have emblems above or below a body line so one more thing to think about if sourcing new used stuff. step side fenders are same from 55-66. some different configurations for spare tire cutaways as far as left or right side of truck. Canadian models have differences compared to USA models. some have different rad support and front fender mountings in the rad support area. Chevy vs GMC can also be different. Chevy and GMC dash is for sure different.

[78classic]

All great info thanks for the input. I also have a 56 parts truck and a 55 driver. I had to buy (4) trucks to get the one I wanted: (59). I was born in 59 so that's what led me to the 59. The other (3) trucks were part of the package. Obviously got more iron than I wanted but what the heck.

The 59 is an original V8 truck although I didn't get a motor with it. I figured I would mess with the 57 first as I kind of like the look of the single head light and the grille and I got it running and stopping, although it smokes like a chimney. Good to know on the sheet metal interchange. I assume all the box stuff is the same (fenders, tailgate, bulkhead...sure looks like it)?

I attached a pic of the 55 it's a 3200 and also runs and stops, but tired as well. The 56 is a roller with cab but I got all the sheet metal with it. It is also a 3200.

The 67 parts truck is a GMC so it has a leaf spring rear end already.

I try to stick as close to a stock look as possible when working on old stuff. I like V8's and automatic trans and that's probably all I will do to the 57. To bad the 56 fenders won't work on the 57 as the 57 and 56 are the same patina color.

I have the passenger door for the 59 but a mismatched drivers door. Sure would like to find one the same color. The 56 doors are also mismatched so can't use those if I want to match color.

[dsraven]

here is a post from the trifive site. maybe help you figure out what you wanna do.
The '57 has two main differences: the side emblem mounting holes are on top of the fender ridge on the '57, and below it on the '55/56 - not too much of a problem to fill & re-drill.
BUT: the grille on the '57s goes OVER the face of the grille opening, instead of inside it on the '55/56. The '57 has a hole & raised area around it that is about halfway up the grille opening (one on the left fender & one on the right). This area has complex tight curves & is VERY difficult to get right if you're trying to make it look like a '55.

[1project2many]

The 55-56 fender will attach to the newer truck although as noted the holes for the side emblem are in the wrong place. The main difference as noted above is that '57 fenders have a flat with a small hole in the grille area that wasn't present on the older trucks. Aftermarket fenders are sold as '55-'57 but are stamped like the '55-'56 parts.

I used repaired OE 55-56 fenders on my truck when I restored it in the '90s. The fenders were already on the truck and I didn't realize there was a difference. I removed the grille braces pictured below and sucked the grille up as close to the fenders as possible. The grille contour doesn't match the fender but I've never known if that's because the fenders are from the wrong year or if it's just the way the old panels were made.

[1project2many]

FWIW my truck is an original V8 4 speed. I kept the stock rear and transmission and for years I ran 225/75-16 tires. Engine rpm was usually around 2600-3000 on the highway with those tires which isn't too bad imo if you're running a short stroke engine. I've switched to 215/70-16 tires and it raises engine rpm about 5%. Maybe one of these days I'll get back to my NV4500 swap...

3.42 gears plus torquey V8 is a good combination. I'm not sure of the years but some GMC trucks from the mid to late '50S used a Dana 45. It's not the same as a 44. Be careful not to grab one if scrounging around in a wrecking yard. Internal parts are very hard to find.