Since CompCams took over they've been redoing the TCI site. Leave it to the Bone Heads to screw up a perfectly good working site, can't find squat on there now.
Good sites for TH350 gears:
If your Rear Diff is Open/Non-Posi.
Jack up 1 wheel and spin 2 revolutions, count the Driveshaft revolutions.
Jack up Rear and spin both wheels 1 Rev and count DS Revs.
= Rear Diff Ratio