Gidday Dodgeman, just to give you a bit of info on the history of the A series 63a gearbox in Australia, they came into the country in the very last of the imported Sunny station wagons ( I think it was about '84-'85 model) My brother actually had one of these vehicles so I've seen the gearbox in the car in person. Interestingly they were behind an A-15 motor.

To my knowledge thats how the ones in the country made it hear.

You are right when you say they were designed for the L-series motor, the spare complete internals I have are from a 180sss gearbox, abolutely identical except fot the input shaft which has the L-series spline on it.

I've got an A-series t50 set up as well at home, so I will endevour to put both boxes on the scales and see which one weighs the most, I'm pretty sure the t50 will weigh in heavier.

Personally, having driven with both and if I had the choice I would go for the 63a gearbox over the t50, the ratio's of the 63a seem better suited for the ouput of the motor of the A-series.