i have the opportunity to buy a used 4l80e out of a 97 3/4 ton chevy 2500 2wd with 40k on the speedo. how hard would this be to adapt it to my 99 nbs z71 with a 5.3? can u change the tailhousing on a 4l80e?

 

you need a crossmember, crank spacer, wiring harness, driveshaft yoke, and tranny cooler lines. Then you need tuning for it to shift correctly.

 

Check to see if it has the ls1 bolt pattern on the bellhousing. You can weld a 6th "ear" on the housing if needed.

 

WHICH WIRING HARNESS DO I NEED? ANMD DOES SOMEONE MAKE A CROSSMEMBER TO go FROM A 4L60E TO A 4L80E?

 

The wiring harness can be bought from speartech, the crossmember can be modified. All you need to do is cut off the mount and flip it around so its pointing toward the rear of the truck.

 

If you are trying to adapt a 2wd 4l80 to a 4wd, you would need to take the trans completly apart. You have to replace the output shaft. The shaft will cost $189 I think.

 

Good catch man, i didn't even realize it was going in a 4wd.

 

A 1997 is the correct case. The oil exit line is in front, return in the rear, and it has the top center hole in the bell.
If your intent was to rebuild anyway the output shaft isn't a big deal but you're probably best off finding a 4WD unit to avoid the extra expenses.

 

Someone also makes a different input hub (or whatever) for the transfer case. When I was researching doing the swap, this seemed much easier than swapping the tranny output shaft

 

you can check out speed engineering for the swap parts and harness too.