8 on 6.5 is standard - the only thing you have to worry about is the newer metric 170x8 pattern, which is like 2003+
8x170mm is on ALL 99+ SuperDutys..... the 97 OBS was the last pickup with 8x6.5
One other thing though... the E-Series Vans still use the 8x6.5 even on the newest vans......