[blucar]

Generally speaking, an OD equipped vehicle will have a lower gear ratio than a vehicle with a standard three speed or auto trans. The 2.78 mentioned in contribution #9 is way to high for an OD.
I have an AOD, 2004R in my '49 Olds 88 with a 3.43 gear ratio, works great. Have a 4L60 in a '64 Chevy, also with 3.43's, runs at 2,000. rpms @70 mph. My '39 Plym conv has a 700R4 with 3.26 gears..
My brother had a '54 Chevy with 350/350 eng/trans and 2.78 gearing, ran good then he put a 2004R trans in it, which I told him not to do if he did not intend to re-gear the rear end. The car will not run in OD below 70mph..
The C4 and it's AOD cousin is an excellent trans if it is properly rebuilt. I have a friend that is a Buick guru, he replaces the old Dana-Flows with either a C4 or the AOD version.
Actually the old three speeds w/OD's work great.. The free wheeling feature allows shifting without the clutch once the vehicle is underway.