Packard Forum Index » Post-War (1946-54)

I realize this has probably be asked several times but my question is will a 1951 three speed od trans fit into a 1950 without to many mods? I figured the case has to be about the same but not sure if the OD governor and coil are in the same spot. I also figured I would have to change out the shift linkage arms on the trans to the 1950. The reason I asked was I found a great deal on a 51 trans and would like to pick it up for a spare if it will drop in. Any info would be welcomed. Thanks for your time.

I believe the rear motor mount is different.

The 50 trans has 2 side mounts, the 51 has a longer tail shaft and a single mount on the tailshaft. They will not interchange.

I have an R11 in my car and it has the side mounts. I believe the R11 is later than 1951.

R11 was first used in Packards mid 48. The trans on ebay are very dirty so hard to say for sure but looking at some pre and post 51 transmissions it appears the cast areas for the side mounts may be present on the 51 and later trans but they don't appear to be drilled and tapped for the bolts. The tail shaft is quite a bit different so there may be some issues with driveshaft fit

The mount could probably be overcome by some fabrication or even a universal crossmember. The 51 solenoid and governor appear in the same location as the pre 51 R11. The lockout switch is different though. Pre 51 it is on the inside knob bracket, post 51 it is on the OD. The older switch can still be used with the later units.

Thinking about it, I seem to recall someone mentioning not too long ago he had adapted a post 51 trans to a pre 50 but he didn't go into details as to what all was involved. I believe his was even a prewar cane shift era car and the cane shifter was installed in the later trans too.

I appreciate all the good information. I may just wait and look for a pre 51 trans then or if I can get it cheap enough I might get it for the OD parts. Thanks again!

Looking at the photos I have if a 1951 R11 transmission in my site's classified ads, it shows the side mounting holes and as I recall they are even threaded in spite not being used.