I found an instrument cluster from a 1991 C1500 gasser that has the better gauges and was wondering what it would take to swap it into my 1988 C1500 diesel? The 1991 has a tach also and what would it take on my diesel to connect the two? When I bought my truck someone had put in an ISSPRO tach, but it gave up the ghost before I got it.

I guess what I meant to ask was: how hard is it to swap clusters from a 1991 to a 1988? Gas to Diesel? I see they physically look the same, just concerned about the electronic part!!!!!!!!!!!!!!!!!

Wont work, Diesels have a different tach sweep.

Well, it may work but your tach will be way off and other things wont likely work.