learjet76 Posted November 27, 2014 Report Share Posted November 27, 2014 Not sure what "P" model I have, so if you can answer that would be great. I am trying to get more top end out of my Plymouth on the highway, is there a drop in gear or rear end swap I can do that won't be intensive? Quote Link to comment Share on other sites More sharing options...
kented Posted November 28, 2014 Report Share Posted November 28, 2014 I thought i saw somewhere someone doing a rear end swap with one from a 90s ford explorer. The supports for the leaf springs had to be move but other than that seemed fairly simple. Quote Link to comment Share on other sites More sharing options...
DJ194950 Posted November 28, 2014 Report Share Posted November 28, 2014 Your 1950 fastback type is a P-19 and Most likely has a 3.9 rear end ratio. A 3 rd. member from many early years will drop in but most were 3.9 or even 4.1. I know 49-50 Ply. Bus, Cpes. came with a 3.73 and I'm sure some dodges any chryslers also did. To find a 3.54 that will drop in best bet would be to look at chryslers 46 and up to maybe mid 50's with a six cylinder motor. Only way to know what yours has now and any other replacements you may find is to look for the factory stamped in ratio on the third member pass. side between the large mounting flange and the drive line flange approx. midway on the side (varies some). Nice looking car! DJ Quote Link to comment Share on other sites More sharing options...
Ulu Posted November 30, 2014 Report Share Posted November 30, 2014 Well you can jack up a wheel and turn it, then watch the driveshaft & count the turns. It can be hard to tell a 3.90 from a 4.10, but if you turn the wheel more times it becomes evident. If you turn the wheel 10 times and the driveshaft spins 39 times its 3.90:1 If it spins 41 times you have a 4.10:1 Simple as pie. Quote Link to comment Share on other sites More sharing options...
DonaldSmith Posted November 30, 2014 Report Share Posted November 30, 2014 If one back wheel is on the ground, wouldn't the other wheel turn twice as much? Maybe count half-turns of the driveshaft, to come out right. Quote Link to comment Share on other sites More sharing options...
st63 Posted November 30, 2014 Report Share Posted November 30, 2014 (edited) You could also dig up a Borg Warner R-10 overdrive unit and bolt it in....factory option in those days, and gives a nice extra cruising gear for the highway. Simpler than a full rear end swap. They're out there if you look hard enough . Edited November 30, 2014 by st63 1 Quote Link to comment Share on other sites More sharing options...
Don Coatney Posted November 30, 2014 Report Share Posted November 30, 2014 Quote Link to comment Share on other sites More sharing options...
Jerry Roberts Posted November 30, 2014 Report Share Posted November 30, 2014 If one back wheel is on the ground, wouldn't the other wheel turn twice as much? Maybe count half-turns of the driveshaft, to come out right. For some reason , it doesn't work that way . Jack up one wheel only . I learned this the hard way . Quote Link to comment Share on other sites More sharing options...
MarkAubuchon Posted December 3, 2014 Report Share Posted December 3, 2014 I used a 1968 Roadrunner, 3;54 kept the perches in place and use offset shackles 1 Quote Link to comment Share on other sites More sharing options...
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