The D7-8-& 9s all had the same starting engine & they were a vertical engine & no water pump. The engine that had a bigger horizonal starting engine than the D6 was the old D17000 V8 industrial engine same bore 5 3/4" as the d7 & D8 diesels had.You know I can,t remember for sure if the D17000 starting engine had a water pump or not but I can,t just remember one on them.I don,t have a parts book to check it out for sure.