Thx I hope this solves the problem

Flat with mild hills I'm not sure "no tag on diff."on gear ratio.In 3rd

No will this coolant temps to rise?I was planning on installing 1.

I have a 1992 Safari/Astro van 4.3L "Z" code non Vortec engine. I'm having an overheating issue @ highway speeds.It runs hot within 10 mins of being on the highway . I'm pulling a 3500lb. trailer. The van has a new waterpump and fan clutch "severe duty" didn't make a difference. ...