1989 Chevy K2500
 

I recently inherited this truck from my father passing, and I am doing some work on it to fix a few things, I am trying to find a combination/multifunction switch for it, and I am not sure if the truck originally came with cruise control, its making it difficult to find a new one to fix it...any help would be great! thank you

Look under your hood for one of these:
Attachment 3596

If you see one, then most likely, you have cruise control. It also looks like RPO code (Found inside the glove box) K30, K34 and K35 are cruise control options. If you have that RPO code, and it is your original glove box, then technically, the truck should be outfitted with cruise control. Then just buy your multifunction switch accordingly.