55.2-59 59 Diff ratio options?

[BlouDon]

If I should want to install a diff with a lower ratio, to get longer legs from my 59 with its 3-sp manual, are there any plug&play options? Eg: Take xyz axle from '75 C10, plug into 59 (I'm thinking replacing the entire axle with another.)

I would just like to be able to cruise 64mph below 3000rpm, the lower the better.

[mr48chev]

The later trucks have a spicer rear axle that is completely different.

The info on GM heritage center 59 truck pfd says several ratios were available in 59 besides the common 3.9 https://www.gmheritagecenter.com/doc...olet-Truck.pdf

Finding a rear end with one of the other gear ratios may be impossible over there though.
More practical and most likely the least expensive is to find a six lug rear axle from a donor vehicle readily available in South Africa with a more friendly gear ratio.
A proper width rear with the right gears out of certain model Toyotas may be your best bet.

This chart shows which of them have 6 on 5.5 lug pattern
https://www.discountedwheelwarehouse..._Reference.cfm

This list shows axle widths for different Toyota models.
https://www.roundforge.com/articles/toyota-axle-widths/

The 96 and up Tacoma 4x4 is six lug and 60.75 which should be close to perfect for your truck and some searching should find mid 3 gear ratios. It would take a driveshaft modification but your cost should be far less than other options.

You have to read between the lines here to decipher the info but the way to figure out what rear axle and what gear ratio the Tacoma have is explained. https://www.tacomaworld.com/threads/...-chart.365138/

Ordering a ring and pinion from the states with the 3.4 or 3.5 gear ratio plus the bearing and installation kit plus having someone do the installation there will cost you around and possibly over 1000 US dollars.

[northerngmc]

Yukon Gear sells 3:38 to 1 for the stock 55T rear end. Pull the centre section out, and swap and ring gear and pinion gear. Took my brother and I half a day to complete.

I replaced my 3:90 to 1 with the 3:38 to 1 and I am happy with the swap. My 59 GMC has the factory 235 and 3 speed. 60 mph is a nice cruising speed now. I don't think that going faster on stock brakes is wise.

[northerngmc]

Here is a link

https://www.yukongear.com/partslist....nion+Gear+Sets

[mr48chev]

That is an option true but remember that he is in south Africa and along with the cost of the gear set, bearing set (install set) he has to pay shipping and excise taxes. along with maybe a two month wait.

I did find that there are two distributors for those gears in my home town one two miles from my house.

[whitedog76]

I'll throw something out there. Being he is in S. Africa, maybe swapping an axle from let's say a Toyota may be an option.

Welding/ fabricating new perches along with the U-joint issue, but may be an option.

https://www.roundforge.com/articles/toyota-axle-widths/

[burnin oil]

Another option is looking for another vehicle with that axle and getting the hogs head and just swapping 3rd members. I know that 3.36 was available in some cars of that vintage.

Another thing to remember with going overseas is that things can get a little wonky. Many australian Windsor motors had Cleveland heads. When I was in Kenya they had a Toyota plant that made minivans. The locals would buy the same model from japan with 200k kms on them because they were more reliable. These were the taxi cabs.

[mr48chev]

Over the years I have seen several claims that you can swap a car (55/64) third member into a 55/59 truck housing but in all those years I have never seen one thatr someone actually did the swap on. It would require a spider gear swap as the trucks use C clips and the cars have axles that have retainers on the bearings and are bolted in.
Since I have have never actually seen it done I am going to figure that it is one of those pipe dreams that guys come up with an a myth that keeps getting perpetuated because they kind of look like they will fit.

For this one I still go with the 96/04 Tundra rear that if you hunt a bit you can find the desired gear ratio, they should be plentiful in So Africa and they have rear drum brakes. Plus his stock wheels bolt on.

The Yukon gear set is 405.07 from Summit https://www.summitracing.com/parts/yga-24144/

Going over to Classic parts the bearing kit

https://www.classicparts.com/1955-62...ctinfo/93-514/ is 299.95

The 3.38 ring and pinion is 348.96 https://www.classicparts.com/1955-62...ctinfo/93-513/

That is 648.91 to swap gears in that rear axle not counting wheel bearings, seals and gear lube plus labor.

[sshamu]

Thank you BlouDon for asking the very same question I was researching.
Big Thanks to Mr48Chev and Northerngmc for sharing valuable and timely information.

[dsraven]

personally, I would recommend the toyota complete axle swap. try to find one with drum brakes and then the master cylinder doesn't need to be swapped out unless it is still the original single system style. like said in other posts, driveshaft mod, spring mounting pads mod, some brake line swapping and a park brake connection. toyota should have the same bolt pattern if you look around for it. grab the old toyota driveshaft or at least the diff connection end of it, for the driveshaft shop to work with when they fab your new one.easier for them and cheaper for you if they have both ends they need to start with. a lot of hydraulic shops would be able to fab a conversion brake suppy hose from frame to axle, here anyway, otherwise a bit of ingenuity could fab a steel line on the frame with the old SAE brake line fitting on one end and a toyota fitting on the other end to connect to the frame to diff hose. doing that will yield a diff and brake system that is easy to find parts for in africa.

[markymark77]

@BlouDon what did you end up doing. Im thinking debating on going with the 3:38 year but still not sure.

[BlouDon]

Originally Posted by markymark77

@BlouDon what did you end up doing. Im thinking debating on going with the 3:38 year but still not sure.

This is what I did:

http://67-72chevytrucks.com/vboard/s...d.php?t=800757