Ok my K5 came with a 305, and well after beating the living crap out of it its gone on to the junkyard in the sky. I pulled it out and replaced it with a 350 that has had problem after problem and well now it sits in my driveway waiting for me to install the next 350 I am getting for it. I have a problem I realized when someone here asked me about ESC(I believe those are the letters). I read in the service book(haynes) that 305s of this year anyway may have ESC and I am trying to figure out what this is? When I removed the 305 it had sensors on different parts of it and I removed them all. The 350 didn't have places for these to be reinstalled so I figured, well I don't have a computer in this truck so it won't be a problem, they were prolly just temp and oil pressure sensors. Well I have discovered I was wrong, i found the silver box under hte dash. I thought that all K5 computers were located behind the glovebox, turns out mine is up dead center in the dash. So what does this thing do and could it be the reason my truck has been running so poorly? By the way my problems have been that I just can't seem to get the timing right no matter how hard I tried. then after flooding it a couple times it got gas in the oil and long story short new engine time. Thank you in advance.