Hi Greg;

We had a very similar truck, 1988 C3500 Crew Cab, 454cid, TH400, 4.10 gear with 235/85R16 tires. 60 mph was about 3300 rpm. It would slowly build temperature at freeway speeds, pulling apprx. 15,000lbs here in Houston.

I ended up with a 3 core rad... Login to read more.