building a mild Daily driver 318

IIRC, there Badger pistons. Yes, stock replacements. Older '69 - 318's have a higher compression ratio. Order a set for that older year engine.

An 8-1/4 should be complete @ that price. Or at least axle flange to axle flange.
I paid $200 for mine axle flange to axle flange with a sure grip equipped unit with 3.21 gears. Adding 10 or 11'inch drums is as easy as the parts store. You just need backing plates to match.