[tommachine73]

I belive that is not rust that you are seeing.I examined your photos and here are my conclusions.In a normal rebuild you would get a new ring gear, pinion gear, bearings including small bearing for pinion shaft,also new bearings for pinion gear crush collar,new posi plates posibly new spider gears if neccessary.The marks you see on the retaining ring is from either a used ring or a incorrect installation tool. The small nicks on the housing can be filed flat and they will be fine.From the looks of the gear pattern the guy got it right.The most important thing is the backlash of the gears too little your rear will burn up too much ,you will hear a clunking noise.By the way I rebuilt my rear about a year ago no problems yet.How do like your A&C ? I built mine about 5 years ago still looks good.