Yep The one serp belt is one of. mybeachside improvements on the later diesel engines

It's pretty much impossible to hook an alternator up "backwards" with reversed polarity. The big terminal is the + and the casing is -.

Now conceivably you could cross the B+ (main output) and D+ (excitation control to the charge bulb) but again that would be unlikely since the terminals are so different in size.

Agreed that you should increase the cable size from the alternator main output, the 240D has such a lightweight electrical system that the cable is way too small for the new big alternator. I would use at least #4 AWG, smaller numbers are larger cable.

All issues are resolved and I'm very happy with the upgrade. I would recommend to anyone. Starting is much nicer and every bulb in my 240 is brighter. the harder part was jamming my arm in the fan shroud & to get the alternator belt to stop squeaking on the glazed pulley.