Rear calipers are noted for parking brake issues. Make sure the parking brake works & the bleed screw opens before you buy a used rear caliper
Audi A3, Golf Mk4/Jetta Mk4 aluminium rear calipers fit on scirocco/rabbit A2 carriers:http://vwcaddyforum.com/showthread.php?t=5312Because the calipers are aluminium and have an improved E-brake, problem solved