i am helping a friend install an advanced adapters sye in his tj this weekend. i have all the tools but have never done something like this before. any words of wisdom?

o yeah and he is giving be his old ax-15 that needs a second gear syncro for helping him. has anyone ever replaced one?

 

you should be fine with what tools you've got.
but however, the AA SYE requires you to press out the stock output shaft and press in their short shaft. that requires at least a 20 ton shop press to do so.
you can take it to a shop to have that done.
otherwise it's easy as removing it and re-installing it once done.

what did he get for a rear driveshaft?

 

he is getting a custom one made at a shop down the street for 200 bucks.
all the things i read didnt say anything about pressing the shaft in. is it the kinda thing i can do with a bottle jack and a trailer

 

this is the install i was going to follow
http://www.links4jeeps.com/writeups/231sye/1.php

 

that write up makes it look pretty easy.
it is pretty straight forward, i guess you'll have to cross that bridge when you get there.

good luck, take some pics.