I'm using RE4R03A out of a Z31 was rebuilt with new parts, the standard bellhousing fits this box, Tailshaft built by Hardy Spicer in 24 hours, slight changes to crossmember, redrilled flex plate to suit converter, and added manual valve body to get rid of TCU and running a guard mounted cooler, been in car behind a 30/25 for nearly 2 years. Good for 600 HP all day every day according to builder plus shift pattern change to P R N 1 2 3 4, and heaps cheaper than C4 or Powerglide, too easy.