Re: I want for my 250 Wellcraft
 

Spare i hate to tell ya but those weren't GM motors the 6.5 and the new 6.6 are both Isuzu Motors

Re: I want for my 250 Wellcraft
 

The 6.6 DMAX is a cooperative effort between ISUZU and GM early on. But the latest LBZ and now LMM are all GM's baby. GM took over assembly for last year when the 365HP LBZ came out, all of it is done in house. But the 6.5 is a direct relative of the 6.2, they share the same deck height and spacing with each other. They even use the same cranks and rods. GM took the 6.2 and made the cylinder walls thicker so you could bore them out more to get the 6.5. The last 6.2's and the first 6.5's were all the same casting number blocks(599), GM just bored the 6.5's out further. I can guarranty you with 100% certainty that the 6.5 is a GM baby based off of the original 6.2 that DETROIT DIESEL designed for them in 81(back when GM still owned DETROIT DIESEL).

And GM relinquished the tooling to AM GENERAL for the 6.5 because the military was tired of all of the 506 casting block failures, and it was part of there contract. AM GENERAL contracted INTERNATIONAL to redesign the 6.5 even further from the last GM revisions in late 98 to the current platform it is today. This is why the latest 6.5's have the double triangle in the valley(INTERNATIONALS emblem). I'm still waiting for the newest revision of the 6.5 to hit streets though. They supposedly turned to the aftermarket to redesign the 6.5 to new mil spec standards, and to meet the newest emissions as well. Rumor is LUNATI is supposed to be making the forged cranks, and the block is supposed to have even more main webbing material added. But it was supposed to be available spring of 07, still waiting.