Working the kinks out of a 240 5-sp that had been sitting for a few years.

Charging system seemed fine until last night. Running high beams, rear defroster, heater fan, wipers I shifted to neutral and coasted through a turn. All dash lights came on at idle and lights dimmed/ fan slowed.

Powered back up and everything fine except the lights flickered and fan slowed a few times. Turned off wipers, heater and rear defroster and it was fine for awhile; then lights began flickering again: worked fine fpor 2-3 minutes; dimmed for 5-10 seconds; repeat.

I expect that this is a bad voltage regulator. Could be a failing diode and/ or voltage regulator I suppose.

I pulled the alternator and went through my spares. There are at least 3 distinct types in this year range: 1) the one I removed which has a bolt extension for a ground strap and a suppressor (? - not sure what it is) on the back with a blade fitting down through a vane; 2) Twin of (1) above but no bolt extension for a ground; 3) Same as (1) but no suppressor.

The old one is a "Volvo" unit and it is different from the "Volvo" unit I pulled from an 89 parts car - which has no suppressor. A Bosch unit from a 90 has different wire attachment points and a suppressor.

Net then: Anyone know why they are different and/ or any guides to interchange? I'm sure I can make any of them fit - eg. ground to the bolt that holds the case halves together - but I don't want to miss something important.
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240s: 2 drivers and some parts cars