Why do you think every large marine engine is a V configuration.
The reason why inline 6 engines are used in trucks bigger than a P/U is because a V8 is too wide for the frame rails. If you ever looked at a V-8 Mack the 500hp engine it was shoe horned between the frame rails. Look at the 8v92 Detroit. Have you seen a twin turbo C-15 Cat the emmissions motor everything is crammed under the hood.
Just because its a inline 6 doesn't make it better look at the big V-12 Cats the V-16 Cats or the old V-12 V-16 Detroits.
I really like the argument that 6 cylinders are easier to work on okay how many of you work on a brandnew P/U truck yourself. Its not like your doing a inframe on the truck. That argument is done like last nights dinner.
You guys live in a false sense of realty with the small Cummins. For one its a throwaway engine, two it was never designed as a truck engine, three if it wasn't for Dodge buying the 5.9/6.7 Cummins wouldn't have a market for that engine. Paccar is using it but no where near what Dodge uses.
The new 6.7 is a even more throwaway engine with its siamese bore and modified block. You over heat that baby once the block is tweaked.