I have an update based on my AU S1 Futura
first i fitted AU2 twin piston calipers with 287mm rotors and they fit under 15in alloy wheels easy, plenty of room, not sure about steel wheels as they have a lip where the spot welds are so may rub, or may not rub
some notes about the swap
it all just bolts on but to get the lower arms in, the front sumframe needs to be dropped, plenty of penetration fluid and a rattle gun helps those studs get dirty and they are long, i left the nut on and use a lever to drop the subframe 1 side at a time.
i also only bolted the sway bar bracket on the outer side using the factory threaded holes and i am using my AU1 master cylinder and have noticed no travel difference in the pedal and brakes work awesome compared to the S1 brakes.
I may have issues when i fit the BA calipers but a new late '99 AU ute master cyl should fix that
second i fitted BA twin piston calipers and 298mm rotors and the 15in alloy futura wheel will bolt up but it scraps in the outer edge of the caliper and mounting bracket, i'd say a pretty easy task to trim but i'm not going to bother as i now have a set of FG turbo 322mm brakes and 17in wheels to go on the old girl as 16in steelies won't fit over 322mm brakes
also if you want to know the different between AU, BA and BF/FG Turbo brakes
here is a set of images
note the turbo caliper bracket sits about 15mm off the rotor hub (has a clear gap) where the BA caliper bracket is only about 5mm off the rotor just like the AU, also the turbo caliper bracket has tear drops where the bolts hole are
AU
BA
FG Turbo
