The Stovebolt Site Forums The Shop Area Driveline What open drive pumpkins will swap into 53 half ton rear end?

I am picking up all the parts I will need some day to do the Driveline swap that I would have in my ideal truck.

I am starting by getting the front and rear end from a 53 half ton that I will be able to put in my 1950 GMC half ton. I am doing that so I will be able to have the more common and easy-to-use Bendix brakes. Currently my Huck brakes are fine but I know at some point I will need to rebuild them so I might as well change the type of brakes at that time. However if I go through the trouble of making that swap I might as well make a swap to more Highway friendly gears and an open Driveline.

I understand that I can change the sm420 over to and open driveshaft by finding a currently open drive sm420 and swapping out the rear parts of it. And at the same time by going to an open Driveline I can get some more Highway friendly gears such as either 373 or 390 gears. I'm having a little bit of difficulty figuring out what years I can use parts from.

My searches have pulled up lots of little tidbits talking about possible swaps but I have not been able to find a definitive range of years and gears that would be found in those years of parts.

Any information on what years I can start looking for for trucks or chassis to get the parts from would be a great help.

Thank you.

If you are only swapping the pumpkin, then 1955-62 1/2 ton are a direct fit.
Of coarse you will also need to remount the axle housing to the springs at the same time.

You can get a 355 rear gear set for the origional axle .That was what i was planning to do to my 54,the only snag i have was i ordered from patricks and have not seen any parts for over 2 years so i have to re order from a more reputable vender.

"What open drive pumpkins will swap into 53 half ton enclosed driveshaft rear end?"
Answer (I think) : none will swap in (If I am wrong, we will quickly see responses)

Drtheo,

If all you want is a Ring & Pinion that will give you higher speeds at lower RPMS, and you want to use the "rear end from a 53 half ton", consider KEVINSKI's advice/post:

- keep the SM420 transmission,
- keep your "new" rear end and "new" brakes

The 3.55 R&P is readily available from several vendors (and from eBay) - and it is immediately available directly from the importer, Mothertrucker.
Buy the installation kit (from Classic Parts, for example) - it includes are necessary parts and at least one of the necessary tools.

https://www.stovebolt.com/techtips/axles/355%20gear%20swap/

It is the best "hidden conversion" on my 1/2 ton enclosed-driveshaft 1954 trucks.

I really like the strength of the sm420 plus I like the sound of the constant mesh second and third gear, call me weird.
So I am gathering up the parts for the 3.55 install this fall in my enclosed driveshaft 53. I'm hoping the 235 will be up to the task.

So, is the sm420 the part number for the original 1953 tranny. By the way, your 235 should easily be up to the task. I put those same 3:55 gears in my 1940 with 216, and it's been great.

SM420 is the "model name/number" of the optional 4-speed transmission that 4-speed GM used from 1948-1967.

http://www.novak-adapt.com/knowledge/transmissions/manual/sm420