I have a 1998 tacoma 4wd, and it is geared with a 4.10 diff. I have replaced both axles and inherited a 3.90 diff along with them. I've heard that it would mess up my transfer case if I was to install this 3.90 diff without changing something in the transfer case... is this true? And if it is I guess have a 3.90 diff for sale.

 

you need to have matching gear sets in your front and rear differentials.

to list your 3.90 diff (those were a 1981 diff) you need to follow the classified rules..