diff replace rebuild

2006 tj, Dana 35 rear axle Took apart my rear diff to replace some seals and a brake part, a buddy of mine told me that I need to take it to a shop and have them put the gears back in because it requires millimeter precision and a bunch of specialty tools. And that if I didn't I was gonna...

I had a noisy rear diff with a TJ 2003 auto 4 speed and occasionally starts to shake when going faster. The mechanicial examined excessively worn out for some parts of the rear diff gear(ratio 3.73 Dana 44) like the axle, drums, clutch packed, diff hat removed and springs loose in diff. They...