[DrKnow65]

helical cut gears are mechanically stronger, they have mure surface area for tooth contact. shimming is more crotical though as you have the usual depth concern but now you also have to account for heel/toe depth too.

Go helical, get some gear setting paste from the local auto parts house, or perssian blue paste if they don't have the yellow gear setting paste (the blue is harder to see). You'll have to move the pinion in and out, the ring gear side to side. Lots of working back and forth to get the pattern just right (paste wiped away from the center of the tooth on the ring gear, center top to bottom and center heel to toe).