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

Pulled my 3-speed from my '48, and pulled my Ultramatic from my '50. I am going to place the Ultramatic into my '48. Do I need to worry about the gear ratio in any way?

You may be the first person on the entire planet to ever do so, but it should go. If your 48 is straight 3 spd it will have a 3.9 rear which they also often ran with the early Ultras, so that will be OK. If your 48 had overdrive it can have 4.1, 4.3, or even 4.56 which is really too much for even moderate cruising. But it is very small potatoes to swap the whole rear and you may even need to change flanges to use the Ultra. driveshaft.

If you can choose, a 3.54 works quite well.