Bridgeport Lead Screw Differences

Good morning folks - I am trying to determine the difference in a Bridgeport lead screw when using an 8F power feed - specifically for a 32" table. My standard lead screw for the 32" table is a total of 42-1/2" in length. The things I have "heard" is that the lead screw when using a power feeder is shorter, a bit reduced in end diameter and has a keyway slot. Are there other differences? Is there somewhere I could find the specific dimensional differences?

Thanks
Rick