Why do American semi-trucks (18 wheelers etc) exclusively use inline 6-cylinder engines, no matter if it’s a Mack, Detroit Diesel, Cummins, or Volvo-built engine?

Question

I get why they are diesel, but why are they all of the inline 6-cylinder configuration? Why not V6 or straight 8 or freakin huge inline 4-cylinders?

In: 715

Answer 1

I work in a mack/volvo manufacturing facility. Fun fact, the 11L and 13L engines Allstars off with the same blocks, pistons, and rods depending on the size, independent of the brand.