That rebuilt a Buick?
Eaton, Chrysler, Donzi, Glastron and a few boat builders used their own selected engines with the AQ series drives.
It's possible that someone used the Buick V-6 in front of an AQ drive.
This might be one of the "odd fire" engines. If so, close attention must be paid to the distributor installation, since the triggering is not equal between cylinders in terms of crankshaft angle/degrees.
I have no idea if a flywheel cover can be found for one.
If the Buick V-6 is Borg Warner capable, then it can be made to work with the B/W flywheel cover and a B/W... slash... Volvo Penta PDS adapter housing.
Personally, I'd not use one, and I'd stay with a more commonly used engine