is this how much the ring gear moves side to side on the pinion gear?

 

No. Its how much play between the teeth there is. If you hold the pinion gear and turn the ring gear from tooth to tooth that is back lash. If you are rebuilding your rear there should be no side to side movement. You do however change backlash by adding/remove shims on the side of the ring gear.

 

thank alot really helps out! going to attemp it this week. we"ll see how it goes

 

This website will help a lot. I followed it and the rear hasnt come apart yet and I beat the leavin crap out of it.

http://www.angelfire.com/theforce/5o...5ohtech001.htm