Originally Posted by mberndt

UPDATE

The D-Series alternator will NOT work on a B-series motor.
I found this out the hard way and had to return the D-series Alternator I purchased to get the correct one, a B-series GSR alternator.

While they look very similiar, the mounting bracket on the D-series is very different than the bracket on the B-series.
The top mounting hole on the B-series alternator is NOT threaded while the D-series IS threaded. In addition, the D-series alternator top mounting bolt hole is almost 180 degrees from the bottom hole, while the B-series is offset and is ~130 degrees.

The D-series bolt gets threaded into the hole from the driver side to the passenger side, while the B-series uses a bolt from the passenger side to drivers side, with a nut on the end.

Also, the amperage rating is higher on the GSR alternator, 80 amps vs 70 amps for the D-series.