Change rear gears Help needed

I have a 2006 Tacoma Off road with electronic rear locking diff.
gears were changed few years ago to 4.88
since then I have had the rear gears get destroyed 3 times. The first time the gear were changed was because of going from 3.73 to 4.88 not due to failure.
the first 2 times they each lasted 2 years and they were installed by "pros"
the third time I installed it and it lasted one year (I know, shocker).
I live in Lemoore CA
I was wondering if there is anybody within couple hours of me that actually knows what they are doing, so I can pay them to fix this once and for all.
Thank you.

 

East Coast Gear Supply. Close thread.

 

Part of a gear install is on the end user as well. Proper break-in is essential!. Did you do proper break-in after the gears were installed?

 

I'll second this. Even though I know how to do diffs, I'll leave it up to the experts.

and to the OP, how exactly are they "failing".