For the caliper check bore, stroke and physical casting/fitment. Starter is again checking dimentions, actuation and fitting. Beware of different teeth-per-inch on various pinions/flywheel ring gear. The unit is electrically capable.
Good - Fast - Cheap: Pick any two.
E23 735i; E30 318i; E32 735iL; E38 735iL; R50 Cooper; R55 Cooper Clubman.
E21 318i; E32 735iL; E34 535i; E38 730iL; E53 4.4i