C-10 is the electronic fuel controlled version of the 3306- it is an excellent, fuel effecient, reliable engine. CAT's class 8 engines are awesome! The thing with the crappy 3126 is people don't realize it wasn't designed or built as an on-highway engine. One thing I have to gripe a little about with CAT is their parts and rebuild costs, regardless of the engine. They are much higher than Cummins or Detroit, and I see no logical reason why.
-Weave-