Originally Posted by usaweapon777
Fuel mileage will vary depend on your gearing and transmission. those getting in the 20's tend to have blazers or half ton trucks. A manual will help get you a little bit better gas mileage. Unless you have a special affection for the 6.2/6.5, or have one laying around, I don't really see why you would do this swap. The amount of time and money your going to invest could pay for a lot of gas for that 454. Unless its on its way out i'd just keep it. If it is going out and you tow heavy loads then consider a 12 valve swap but those engines tend to go for a good bit of cash as well. I love the 6.2/6.5's and own one as well but I just don't see it as a practical swap over a fine 454.
I also plan on hotshotting in this truck around I my state. I talked to a guy that does the hotshot jobs and he said my truck is the best truck to use. So loads of 5000-20000 is reasonable he said. And the only 5.9 cummins I've found around here are selling for $5000-$6000 I just found a guy the other day that rebuilds 6.2s for power and I'm going to get a quote from him