I don't know if it was the same from 54 to 55. but I know of three ratio's right off the top of my head because I've had three 54's, 6cyl car had a 3.92 to 1, one of the v-8 or should I say Yblock cars had 3.31 to 1 and the other had 3.55 to 1. I think it's an 8 or 8.5 inch. it's and open diff so only pulls one at a time. I went completely through the one I have pics of on my photo gallery, new bearings and just inspected all the gears. It has stood up to reasonable abuse, no john force burn outs but it has been stomped on. since the original Eng put out 130 hp and we are now running a 66' 327 and a built 700r4!! I think it is holding up quite well!! If you still have usable parts what ever they are don't let'um go to the crusher pleeeezzz.some of this stuff is getting hard to find at a reasonable price!!!

Brian