Yep, designed by detroit diesel way back in the late 70's. The 6.5 is nothing more than an overbored 6.2 as well, many of the first 6.5's had the same blocks as 6.2's(599 castings) and some of the 6.2's from 91-93 have been bored to 6.5's as they were the same blocks. In late 99 when GM started on the DURAMAX they sold the rights to the military and they contracted NAVISTAR to build the 6.5's for them hence the NAVISTAR diamond in the lifter valley on all of the late model 6.5's.