Maybe take the diff apart, clean it and post pics first
U may be able to lock it without totat destruction of if
It may pay to post some more pics of the actual diff
U only have to lock 1 shaft to the housing and its totally locked
As in u may be able to make a cheap diff lock
I've heard of the Lincoln locker but we call it the cig locker
It's a performance upgrade for the 18 yr olds $500 drift car
