I am going to rebuld a used trans becose the diff pin cameout and destroyed my trans caseing. is there any thing i should know about the rebild?? im going to have the diff pin welded in. what else should i know about??

Well, that's a really open ended question. Opening the tranny if you never have can be tricky. It's hard to crack open after you get all the bolts out. I had to gently tap around the seam of it with a ball-pin to break the anarobic sealer just to get it to lift off. When you open it, you have to lift straight up perfectly b/c it sits on pins. Definitaley drain as much as the tranny fluid as you can before you attempt to open it, or you'll be a mess. The gears and gearing inside are pretty obvious and they only really fit together one way. Depending on what your replacing/rebuilding will dictate how complicated it will be. There is a small ring bearing, it kinda looks like a braclet, be careful with that. It can break VERY easily and then you HAVE to buy a new one - it can't be re-assembled. Be sure to get the right anarobic sealer when you close it up, I believe it's part# 51813 and make sure you have a continuous bead around the housing.

That's all I can think of off the top of my head. Hope that helps. If you have more specific questions post them up.