Rear Pumpkin

[hkestes41]

Question. Will the rear center section from a 55 Savoy fit in a 48 P15 rear? Or could the ring and pinion from the 55 be swapped into the 48 center section?

[Plymouthy Adams]

as I understand it they must be within within a certain ring and pinion size for the housing to be compatable...state your gear size...from and to.....and also the axle spline count had undergone a change in that time frame...you may have to swap side gears..

 

per my interchange the axle for the 53-56 Plymouth uses 16 spline axle and the earlier use a 10 spline axle..50 through 56 use the same length axles with same bearing land dimension and same axle spline diameter

Edited February 26, 2013 by Plymouthy Adams

[hkestes41]

Thanks Tim,

 

I don't have the 55 center section to measure anything so was fishing. Found one for sale with 3.54 gears which would be good to have. Will have to see if the seller can measure for me.

[Plymouthy Adams]

two type of differntial cases are used in the Plymouth per my interchange..all ratio's under "A" interchange and those under "B" interchange..gear sets withing "A" will not interchange with "B" unless the case is also changed...

 

3.9  3.73 and 3.54 are in contained in set "A" 

 

 

set "B" uses the 4.1  4.3 and 4.78 gear sets 

 

it makes reference to the case difference being the use of 4 side gears for the heavier ratio per the 2 side gears on the lighter application..you can move to 4 gear on interchange but not recommended to to go from 4 to 2 though it infers it will work..load may cause early failure (1953-56)

Edited February 26, 2013 by Plymouthy Adams

[hkestes41]

So then If I understand correctly that is saying that if I currently have the 3.90 gear and will swap the my current side gears into the 55 center section it could well be a go. 

 

On the other hand if I currently have the 4.10 gear I could swap my current side gears into the 55 center section and it may work but could cause early wear and failure.

 

Wonder what they consider early failure?

 

Guess I need to crawl under and determine for sure which gear I am currently running.

[Plymouthy Adams]

the note is by design of the corporate engineers..x weight/load gets 4 side gear...lighter gets 2...if you go from 4 to 2 and stay with the same weight/load, yes you could experience premature wear/damage thus the interchange warning...

 

if your pumpkin is the 3.9 as most of these are unless sold in hilly area..then the 3.54 is supposed to work by the interchange chart..but the side gears will be different spline count and will require the gears to match your axles..and by what I am understanding..the side gear carrier is larger in physical size and thus will not fit the smaller gear housing,...I am not sure of the housing dimensions say hoghead bolt pattern, bulge depth or hoghead physical deisgin...I would think the note would not be needed if the hoghead bolt pattern is different as it would not slip in to begin with...I must say I have no knowledge personally one way or the other...thus I just posted what was in the catalog of interchange..

[Young Ed]

I've only seen the 4 side gear used in trucks but I wonder if 55 and the v8 brought it into the cars too. I believe my WC had a 4gear one and I swapped it to a car one. I've only hauled a few times but so far its fine.

[plyroadking]

I bolted in a' 55 3.73 3rd member to my' 40 Plymouth original rear end housing . Only problem I had was that the' 55 axle shafts were too short the reach in and engage the 3rd member. The 1940 shafts slid in and fit perfectly. Only noticeable difference is the faster speeds and the dual fill plugs....

[Young Ed]

I bolted in a' 55 3.73 3rd member to my' 40 Plymouth original rear end housing . Only problem I had was that the' 55 axle shafts were too short the reach in and engage the 3rd member. The 1940 shafts slid in and fit perfectly. Only noticeable difference is the faster speeds and the dual fill plugs....

 

Are you sure it was a 55? Or did you change the side gears? I've done two 3.73 swaps from 53-54s into p15s and had to change the side gears.

[viejito1937]

does anyone have a carrier assembly 3.73 from 1949 1950 plymouth. im trying to swap third member out on my 37 dodge. I currently have 4.10

[Alexander]

I have a 3.9 that I can offer you

[viejito1937]

thanks for the reply, i really want a 3.73 carrier assembly if all possible. what did 3.90 come out off? how much r you asking for the 3.90, worse case scenario if i cant find 3.73. thanks!

[Mark D]

two type of differntial cases are used in the Plymouth per my interchange..all ratio's under "A" interchange and those under "B" interchange..gear sets withing "A" will not interchange with "B" unless the case is also changed...

 

3.9  3.73 and 3.54 are in contained in set "A" 

 

 

set "B" uses the 4.1  4.3 and 4.78 gear sets 

 

it makes reference to the case difference being the use of 4 side gears for the heavier ratio per the 2 side gears on the lighter application..you can move to 4 gear on interchange but not recommended to to go from 4 to 2 though it infers it will work..load may cause early failure (1953-56)

 

George Asche just had this same conversation with me a week ago.

[Frank Elder]

George Asche just had this same conversation with me a week ago.

I'll bet it was longer too!