Tony are you sure it's not 597?
Ken
Rear Axle
589 - 3.23 open, 8 3/4, 10" rear drums - front disc
591 - 3.55 s/g, 8 3/4, 10" rear drums - front disc (A36 Pkg)
592 - 3.23 s/g, 8 3/4, 10" rear drums - front disc
593 - 3.23 open, 8 3/4, 11" rear & front drums
594 - 3.55 s/g, 8 3/4, 11" rear & front drums (A36 Pkg)
595 - 3.23 s/g, 8 3/4, 11" rear & front drums
596 - 3.54 s/g, Dana 60, 11" rear & front drums (A33 Pkg)
597 - 3.54 s/g, Dana 60, 10" rear drums - front disc (A33 Pkg)
642 - 3.91 s/g, 8 3/4, 10" rear drums - front disc (A31 Pkg)
643 - 3.91 s/g, 8 3/4, 11" rear & front drums (A31 Pkg)
644 - 4.10 s/g, Dana 60, 10" rear drums - front disc (A32/A34 Pkg)
999 - 4.10 s/g, Dana 60, 11" rear & front drums (A12 Pkg)