[jmack91z28]

No, you're right, it wouldn't get near as good as mileage as a 4bt. But when you factor in cost difference in fuel, it's not quite as good a deal you know? For the money and time spent that is.

I think a 261 or 292 will put out as much torque as an old 4bt, and a lot more hp. But then it has to do with where the two engines are making torque, how the truck is geared, transmission, etc.

My 6bt doesn't feel like it's really making any power till about 1700 rpm, then after 2300 rpm it's basically making a bunch of noise and not doing anything haha. So you've got such a small powerband. I know you can mess with the governer spring and all that fun stuff in the IP and "turn the fuel up", but I just haven't yet.

A good running stovebolt with a newer style HEI ignition and the such, coupled with a 5 or 6 speed, geared correctly should produce respectable power numbers, tow what you'd need within reason and probably get 20 mpg highway.

I'm not knocking the cummins option, just giving an alternate view.