The Stovebolt Site Forums The Parking Lot Tons 'o Fun Rear end swap- Ideas?

I'm wondering if any of you guys can get me pointed in the right direction. Patricks had a ring and pinion kit for converting my 51 Chevy 1/2 ton to "highway speed capability".
They don't offer the same capability to the 1 Tons, so I'm looking for knowledge of what kind of rear end will fit under my frame (retaining 8 lug setup) 49 GMC 1 Ton? Does anyone know what sort of rear end/vehicle I should be looking for as a donor?
Thanks
Dennis

The 1/2-ton kit from Patrick's won't help you as you already recognize.

You have two basic options as I see it.

1) You can change the gears in your current rear, going to the standard 3/4-ton set which is 4.57 instead of your current 5.14, or searching out the hard to find 4.11 from a later truck using the Eaton rear.

The 4.11 (4.10?) gear set is hard to find by all accounts. You may happen on one easily, or may never find one. I know a guy who was given one for carrying it away. Other guys have searched high and low and not found one anywhere.

There are rummors of a gear set more like 3.70 but no one has ever convinced me they have found an Eaton gear set in that range. I think they have confused it with a Dana rear that was used under early 70's 3/4- and 1-ton trucks.

2) You can change the entire rear axle. This opens up lots of options and means dealing with some questions.

First the options... They are many. The Dana 70 series of axles seem a good choice as do the GM 14-bolt rears. There may be others. When I changed mine I chose a GM 14-bolt mostly because I had one that already had the right spring pads on it and a gear ratio (3.54) that I liked.

The GM 14-bolt comes in two widths if I remember correctly and you'd want to shop for the one that best fits your needs. There is a semi-float six lug version of the GM 14-bolt and you don't want one of those.

I have a couple of Dana 70 HD axles on hand and one is from a dually pickup and far too wide to go neatly under my '55 1st 1-ton. Both my Dana's have 4.11 gears though I don't believe that would be difficult to change.

The Dana was used under more different trucks than the GM axle. You might find it under a Ford or Dodge and will definitely want to have thought through width and brake issues before going shopping for one. Do you have a pickup bed with fenders or a flat bed? If a pickup bed you really do need to be more careful to get the right width axle.

Some things you need to think about before axle shopping are gear ratio (easier to buy the one you want than change), WMS to WMS width (how wide do you want to be?), and brake type because the axles are available with either disk or drum brakes.

I mentioned the 14-bolt I put under my truck. I'm running a Cadillac 500 with a TH 400 and do not expect to have any trouble moving a load. I got the axle from under a '50-ish 1-ton with a tired 216 and an SM420.

The guy I bought it from was selling the truck because it was not capable of hauling a load and was difficult to move even empty. Now this was a tired motor, but the issue remains you need to have carefully considered how you are going to use the truck and make sure you've matched the gear ratio you choose to your needs and available power.

If this truck runs around empty, but is powered by a tired 228, your best bet may be to look for that ellusive 4.11 gear set. You'll have a drivable truck that will run down the highway, but not give up so much torque multiplication that it requires a granny gear start. I don't know how badly that 216 ran, I never tried to start it.

So that should give you a start and someone will come along with something I missed or a different opinion...

I found a Dana60 with floating axles out of a 77 f-250. It has a 3.54:1 ratio that I like and is only 2 inches wider with my 17" rims on it. Not noticeable under a flatdeck. I will have to move the sprind perches it a bit but the stock u bolts will work. Im not sure but I dont think Im going to need a convertion U-joint. Plus you get better brakes with easy parts avalibility.

Hi,

I bought a 3.90 rear end from Patrick's several years ago to swap with the 5.14. I don't know if it's an Eaton or a Dana or what, but it was a drop in. I'm sure Patrick's could tell you what they've got that will fit. I can now do over 70 mph.

Wilber

Can you post some pictures of that rear with the 3.90 gears? That would help identify it quickly.

HI:
I just did a swap out on my 1946 1-Ton Chevy panel truck. The rear ends (third member pumpkins) on the Eaton 8 lug full floating rear ends will bolt right in for Chevy 3/4 tons up to 1972. I found a 4.11 through the stove bolt site. The 4.11 gear ratios were used on most trucks with automatic transmissions. There is also the elusive 3.90 gear ratio set out there but impossible to find. There is some sacrifice doing this.
The good:
You can reach 65 MPH on the freeway with about 2600 RPM and 32" tall rear tires.
It bolts right in...you can keep you 8 lug stock wheels & hub caps /tires.
The drive shaft stays the same length.
The negatives:
Going up a hill you MUST use the lower gears, especially with a load. ( I just put 1600 pounds in my panel and had to go home in third gear.
The change over cost me $300.00 for the pumpkin plus $260.00 to have it installed.
I am glad I did it!
Brian