my truck is a 1995 chevrolet k-3500 4wd. 4.10 gears. auto trans. the engine has the dual thormstats. h.o. water pump. 153000 miles ive had it since dec 2009. here in southwest kansas. even at 100 degrees it never even runs warm....the only mod i have did to the engine. was put a boost gauge on but before me who knows? i know in 2009 it had a new injector pump put on pump number is 5288. with a green tag ,on one of the bolts.