Can I swap the cluster from a 94 into an 89 or do they not work?

I would think the swap is a go. 

Edited October 22, 20178 yr by john in KY

Awesome thanks. One has a tach and one doesn't, would I need to add anything or nah?

My 93 had no tach, and only oil light.  Swapped in an older gauge set that had both.  Had to change the sender to the pressure gauge type, but the same wire was used.  Don't remember doing any other wiring additions, and the tach works.