P4 differential swap

[elmo]

one thing that WPC did was not change things to much , although he did improve on quality , if you can source a later 1950,s 6 cyl diff its asimple job to chang e over , just draw the  axles , unblot the diff head and replace with the later model diff head , i,ve done it but please before you do it check everything out, personaly i have found that any 6 cyl mopar product from 1937  up to the late fiftys early sixtys  , most diff heads  will interchange

[Jim Yergin]

Phred,
You might want to go to the site listed below and do a search on the questions you asked. There has been a lot of discussioin and information on thoise topics on that site.
http://www430.pair.com/p15d24/mopar_forum/
Jim Yergin

[Phred]

I would like to change the gearing in my P4 (37 4door), as the engine is really spinning at 50 mph and 4.1 differential. What are some changes and approx costs to make them?

Overdrive? Is this a simple bolt in addition?

Ring and Pinion change? Is there a 3.73 or lower gear that will bolt into my existing axle housing assembly? Is there a complete rear end from a later year that will bolt up to my driveshaft and/or backing plates?

Is there a modern 4 or 5 speed overdrive transmission that can be easily used? Are there any kits?

Other ideas?

Thanks in advance!