4wd problem
 

a few years ago i had a used tranny installed in my truck, but before i had it installed my 4wd worked, but after the tranny was installed and when i shifted the 4wd in 4-high nothing engauges.. so wondering if someone would or might know what could be wrong, the transfercase is working just fine, could it be a actuator linkage? if someone can help me that would be awesome!! thanks