Alternator Pulley wrong size

[Praxiss454]

Hi folks,

Trying to figure out why my belt isn't straight, and I realized the pulleys on new alternators are the wrong size for our trucks.

Here is an OEM style alternator pulley (photo credit to jdl71):


And here's what the pulley looks like on a new one from the store:


As you can see, on the OEM style pulley, the belt groove is about 1/2" farther forward. When I install a new alternator, my belt is misaligned. So what gives? I do not have an OEM pulley and have not been able to find one anywhere. Any tips on how you handled this problem are much appreciated.