anybody know of a tech writeup on a Spool install (Yukon is what I got)

thanks

 

its exactly the same as the install of any other locker or lsd that replaces the carrier i.e. detroit locker, supra lsd, truetrac, ARB(much simpler, although), etc

you will need to:
disconnect the rear brake lines, including e-brake cable
remove the 4 bolts on each side and slide out the axle shafts
disconnect the driveshaft
remove the 3rd member bolts
pull the 3rd member(its heavy, be careful)

now, i assume you have never set up a diff before, since you are asking this question. since you are replacing the carrier completely, i recommend that you take the 3rd member to a reputable diff shop and have them install it to make sure the proper preload and backlash is set up.

after that, the installation is reverse of removal.