In theory the angle is slightly different. That is what I was told.
Bridgeport part number 11182120.
Usually the motor adjustable vari drive bushings give out first. If not attended to, they will destroy the motor shaft. Very old machines had thin black plastic inserts epoxied in. Newer machines have the thicker aqua colored inserts which are not replaceable. When rebuilding a head, I use factory replacement varidrives, because I cannot glue the inserts back in so there is no wobble and it is in balance. I usually do a top end kit of the bearings, belts and drives so that that part of the machine will be good for another 6 years or so.