Hi i replaced my 305 with a 350 and I didn't change the PROM chip. Recently I have been looking into getting one from a salvage yard or somewhere very cheap. I was wondering if there are any vehicles with the exact same chip as my 93 K1500. Ex. 93K1500 or 94K1500 or something close.

I got mine from tbichips.com not cheap but good stuff!! about 120.00 bones

It will cost some $ but I replaced my stock prom with a Jet stage 2 and love it more power and better mileage just remember to get a low temp thermostat when you replace it jet makes one for it.

I got my performance chip from tbichps.com as well, I got the stage 1. Low end performance kicked up a bit, acceleration seems smoother. My MPG didn't drop off at all. $70 or so, I think it was worth it. I believe his FAQ may answer your questions about the swap as well.