"With a little modification, they can be made to fit a 54."
What is needed in 1954 is an earlier 4.11 1/2 ton truck carrier for the ring gear. Just swap it in.

"However, the 55 1st and later is an open drive shaft and requires a completely different gear set. I agree with Tim. If there is a 3.55 gear set made for an open drive shaft, I have never heard about it."
There is a 3.38 R&P set available for the later, open-driveshaft 3.90 rear ends.

Here are some sources (MT does not sell a set - unfortunately):
1. https://totalmetalinnovations.com/i...p;zenid=5587fdb8114a7f23a30f08424d7de76b
2. http://www.justdifferentials.com/GM55T-338-NG-p/gm55t-338-ng.htm
3. http://www.classicparts.com/1955-62-Rear-End-Gears-338-Ratio/productinfo/93-513/#.VwvaoRMrKdE

Installation kit #1 (get one of these two kits)
Installation kit #2 (get one of these two kits)

Patrick's 3.38 R&P gears - could be slow to deliver

Tim
1954Advance-Design.com
1954 3106 Carryall Suburban
1954 3104 5-window pickup w/Hydra-Matic
The 216 and early 235 engines are not "splash oilers" -- this is a splash oiler.