Just found out that my pinion bearing is bad. Based on the vibrations it is possible that the case is also worn. (Vibrates on accelleration as well as right after you let off the gas) What is the best way to tell what gears are in the rear end? What gear ratios came in the 55-59 chevy trucks? A friend mentioned that it might be better and cheaper to replace the rearend with one that has higher gears. What is a good rear end for a swap? I am looking for something that would just bolt right up.

Make sure the pinion nut is tight to start with. The rear ratio is going to be 3.90, if it still has the original in it. If you change out the whole unit than I would find a 67-70 rear. You will have to cut off the old perches and weld on new ones. I did this swap on my 59 and it worked out well. Chris

Thanks. What gear ratio did you swap for? I have the three speed tranny with the two speed borg warner OD. Do you think it would be worth swapping the 3:90's for something higher like 3:50?

you need to take the cover off and inspect everything. if the pinion bearing is toast odds are the rest are too, its only 50y/o......... once you have the cover off roll the ring gear around and you will find a tooth count stamped on it. 41 11 is 3.73 and so on, divide the larger by the small and you get your gear ratio.

3.73 was the ratio of the rear end I put in my truck. I wouldent go much taller than that, unless you like to cruse at 95.

Fast Reply Needed. Rear end gears are toast. Ok... Just found out the bad news. My truck is in the shop and I need to decide on a ratio. The rear end gears are toast. I found out that the current gears are 373's via the spin test. I have a 327 with the camel back heads and a 3 speed manual with a borg warner 2 speed overdrive behind it. I have been thinking about going with 355 gears. My concern is that I won't be able to pull a trailer very well. I have to lock out the overdrive when towing anyway so the overdrive wouldn't be an issue in that circumstance. Does anyone know the ratios on the 3 speed tranny? How would it do out of the hole with 355 gears vs. 373's. Any thoughts and opinions would be appreciated.

Available Gear Ratios for Stock Rear End. Thanks to all for the help. I found out some useful information that you all might want to know. Originally I thought that I had 3.73 gears via the spin test. One of you said that they were 3.90 gears After looking all over the internet I found only two gear ratios (3.90 and 3.38) for the 55T rear end... which is what these trucks have. The 55P rear end which is for passenger cars has tons of ratios available in such case I would have gone with 3.55's. Our sponsor site has 3.38 ring and pinion set but I opted to go with the 3.90 so that I wouldn't lose towability. With my borg warner overdrive I can cruise at at least 65 mph real easy. Just thought you all would like to know what I found. Thanks Again for all your help. Derek