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Does an R9 overdrive tranny have the same size input shaft and bolt pattern as a 38 standard 8 tranny?

Yes.

Wow that was quick

I don't waste time!! As far as I know, all Packard transmissions from '35 and up have the same spline input shaft, which BTW, is the same as a 10 spline Chevrolet. There was a transmission that I believe was for the Senior cars that have 5 bolt holes, but I think they'll interchange, you just don't use the bottom 5th hole. Try and find a '35-'39 floor shift trans, and you can swap the tops with a little modification with the later year transmission's, up to '54.

G'day Phil and all, As we know, there was no optional overdrive in Packard for 1938. A few ( myself included) have fitted 35 -38 floor change tops to R6 and R9 overdrives. I am not sure if your reference to a "standard 8" means the 320 Cubic inch standard eight motor. If this IS the case then the only floor change that you can fit to a 38 Super is an R6 or an R9 with the correct big input spline and one year only 1939 bell housing, much different to a Junior R6 or R9. The R11 is a side shift trans and you will need to acquire a "slick shift" from the Fifties to run a funny looking floor change. The R6 has only a solenoid, with no governor, works in reverse to a R9 and R11 and needs a bit less chassis modification to fit. The R6 has a crap crush washer in the rear of the trans so there are definitely trade offs in fitment. But the 28.7% reduction in revs gets the smile on your face every time. We got 20 MPG ( imperial gallon ) on our last long trip averaging 60 mph. Good luck Peter Toet

Can you tell me what frame mods have to be done?
I would like to install an overdrive in my 38.
Do you have to machine anything?
Which one would be best,R 6-R9 ?
Thanks.
Richard

G'day Richard, It is much easier to fit the R6 or R9 trans to the Six than the Eight. The next time I put the cars on my hoist I shall take some pics from underneath. As for which one is best, I prefer the R6 as you do not need electrics fitted to engage the overdrive. You do need electrics on the R6 to dis-engage the overdrive above about 17 mph. The R9 uses the solenoid and governor to engage and dis-engage the overdrive. I suggest that you find a mate with a spare chassis to have a look at the work requred. There is a fair bit of work to fit to a 37 120 for example. I shall try to get more info to you. best regards Peter Toet

Thanks Peter !!
Photos would be fantastic.

I'm familar with the OD that Studebaker used,I have one in a Stude Pick up.It use's an electric govenor and is cable operated also.But it doesn't look like it would be a great swap for my Packard.

I looked into the Gear Vendors unit and it didn't look like something I wanted to "make fit".

Useing the R6 with my shifter cover sounds like what I'm looking for.
Does anyone have info on a smaller ring gear for the diff ?
Thanks again,
Richard