Hi Malc,
I assume they are series motors, identical designs. Then when in series, they will be forced to have the same load; that is current therefore the same torque. So if you take more torque from one motor shaft for accessories than the other, one of your drive wheels will get a little less torque. I don't really have any idea if that would be noticeable to you or not
Which Prestolite motors are those?
major