The one in the junkyard came out of an 89 S10 longbed with 4.3/auto, so it will work in my Blazer. I'll check on the blank Eprom part number, if its still there. My Blazer already has a 160 degree stat, and my truck has a 180 degree one. The Blazer never gets to 210, even with the A/c on in 95 degree heat! I may be going back to the 4.3 in my truck, as the 355 is suffering major blow-by, and insists on reaching 260 before the thermostat opens! I believe the coolant passage is blocked somewhere. Plus I have all kinds of exhaust leaks, and my rearend is showing its age (172,000 miles) with increased backlash, and the Cv joints hate the V-8, so does all the IFS, it blows the seals out constantly. So, I'll probably go with rebuilt heads and a low-mileage short block 4.3 in it, and rebuild the rearend, and possibly look for a Dana 30. The 4.3 won't be stock, mind you- probably an Edelbrock Intake, 1.6 roller rockers, headers, Jacobs ignition, etc. Just a mild 4.3.
1989 S10 4x4 355(soon to be 4.3)
1989 SBlazer 4x4 4.3