Hello friends, about 4 years ago my 45 GMC was hit by a distracted driver who came into my lane and struck my truck in the drivers rear fender and ripped the diff out, i'm now just about ready to install my new diff and i'm looking at what ratios will fit, the housing i have now came from a 58 chevy wagon, when i built my truck i changed the diff to a 58 to 64 diff, the diff came out of a 46 chevy a local guy had taken out, so i'm not sure of the year, so after looking around online i figured out it had came out of a 58 to 64 chevy car i think, here are a couple pics of the pumpkins i have, the one with the 55 at the end was in my truck when it was hit, the one with the 63 is out of the wagon diff i bought as a replacement, one looks to be a 3:36 and the other a 3:55, is the 55 and 63 #'s the year they were made and what ratios will fit into these housings, thanks for any help, Lawrence
Look on the outside of the housing for a casting date, such as B 23 9. That decodes as B = second month (February), 23rd, 9 = 1959 (last digit of year). I've seen month-year, but not just a year number stamped, so the 55 and 63 numbers might be a year, the letter might be a month, 55 A would be Jan 55, L 63 would be Dec 63 (1964 model year).
i just pulled another one apart, it is a 3:08 i guess. i'll look for the casting marks on all of them, i have one more i can pull apart but will i find a higher ratio?
3.08, 3.36, 3.55 are the "highway gears" that they made for these. Won't find any lower number ratios that I know of.
thanks squirrel, i guess i'll go with the 3.08s, there is a little rust on one axle gear, can i change just that one gear or should i change both and the spiders, can i even get the axle gear out without pulling the carrier?
Back in the early to mid 60's when I had a beat up 55 Chevy with a 389 Poncho in it I used to break these rears[especially the spyders] on a regular basis. I had always heard that stick shift wagons came with 4.11's. The local boneyard had a lot of old Chevys and sold the center section for dirt cheap if you removed them. One day I spotted a wagon come in so I immediately checked it out and it was a 6 popper 3 speed with O.D. Here was my 4.11's so I thought; couldn't wait to get it ripped out. It turned out to be a 3.55, It actually was the only 3.55 that I had found all the others were either 3.08 or 3.36.
FROM THE FACTORY IN 1955 there were ONLY 3 gear ratios: 3.55 (Powerglide tranny), 3.70 (3sp), 4.11 (3spOD).
The Jalopy Journal
