Tell me about it.
With all the attempts I've done at improving it I could write a book of things that seemingly DON'T work.

Had hopes the high cr 360 engine now in the car would be more efficient, but I'm still not seeing it happening.

I'm currently kinda blaming the transmission (A518) and the perhaps in-efficient / old design(?) '60s stall convertor (non-lockup) I've used in it for the crappy mileage the car is getting.

I have a 42RH (OD+LU) needing to be rebuild. It has a matching '90s convertor which is also 1" smaller in diameter (less weight / more efficient?).
Hope this trans will be able to 'fix' the mileage issue with the car.