swapping the instrument panel
 

I read a post here a few weeks ago about installing a gauge cluster with a tach, into a blazer without a tach. I searched, but all that came up was for the 2nd gens.

If I were to find a cluster with a tach for my 93, from maybe a 87/88, or whatever years had them, is it a plug and play swap? I know some of them had electric speedos, and some had cables. What are the other non obvious differences?

Would I have to wire anything for the tach to work? What would I need to do to swap one into mine?

i went to do the same thing to my '92 Jimmy (like 10-11 years ago), and ass far as i remember, you just need to plug it in-the wiring is already in the wiring harness, and the clusters will match up the routing needed.
i actually installed the cluster in my truck, but took it right back out, i didn't like the way the factory tach cluster looked . now, my '92 was a factory 5 spd (and it had that BS "shift" light in the dash), so maybe that's why it worked, not 110% sure.

i used to have an 88 s dime and the speedo in that was a cable, it think they changed in '91

you had an '88 with a speedo cable? funny, i swapped a 4.3 into an '87 2.8 Blazer, and it was electronic.