One more thing - obviously you are taking a chance with junkyard alt's, so try for one with an exchange policy. When I took the PnP 70Amp to an auto parts store, the guy had to thumb through his test machine book at length to see how to hook it up. He then pronounced it DOA.

I didn't want to believe this, so took it to another store of the same chain, where the grey-haired counterman didn't need to refer to a book. He quickly connected it to his machine and said it was just fine. And it's been running for 4 years now on my son's car.

Get a second opinion if it "tests dead".

I believe the 1986-on 240's all had 80Amp units.

--
Bob (son's 81-244GL B21F/M46, dtr's 83-244DL B23F/M46, my 94-944 B230FD and 89 745 (LT-1 V8); hobbycar 77 MGB, and a few old motorcycles)