Bridgeport Boss stepper motors question

Hello, I was hoping someone here would know:

1) The steppers on the bridgeport boss mill look like size 42
steppers but have large finned heatsinks enclosing the body of the
stepper motors. Did they run these stepper motor harder that typical
so as to need extra cooling?

2) I do not see any current rating for the motors, what is the rating
for the motors. Will these older stepper motors run OK with PWM
chopper drive?

3) If the motors are upgraded, can the motor heatinsks be easily
removed and mounted on the replacement motors?

Currently I have this mill sitting in my garage, I have my chopper
driver design entered in orcad, still tweeking it some.

Thanks for any help on this. Stan Krumme KO6YB