Okay I have a major project that is just about done. The truck has a 6.2 diesel and 700R4 that were swapped (it is 4wd as well btw) before I bought it. The guy who did the swap never hooked up the lock up system

and I have no idea what components make that up.
Second, I HATE the way it shifts. It's really sloppy. I have heard positive things about shift kits. I have a trans filter/gasket kit that I was going to install soon so I want to address it then.
So basically I have 2 questions:
1) What do I do about the lockup system? Junk yard and try to piece it together? Or use a kit?
2) What shift kit is the best for a diesel? And how hard is it?
Thanks!