Here’s my 51, 3100 with a 5.3 LS while it was under construction. Like you I didn’t have room for a fan on the engine side of the radiator. I called Vintage Air’s tech line and they recommended the correct CFM fan for mounting to the condenser in front of the radiator. I don’t remember the exact CFM rating they suggested but give them a call as they are very helpful.
The fan is wired so that either the engine coolant temperature sensor or the AC Trinary Switch can activate the fan. Like Mark, I installed the biggest CFM fan I could find.
The truck is finished now and I have 170 miles on it so far. I’ve experienced no overheating issues and I have driven the truck in 100 degree weather, although not in stop and go traffic. Hope this helps.
Dan
35 CC Case 38 Chevy Pickup 51 3100 AD 58 3100 Apache Fleetside
