[piecesparts]

I get 14.5 to 15 MPG with my 3.73 12 bolt posi setup. I am runnning a 385 stroker engine, with a 700 R4 tranny (Without the lockup converter). I am running a 2400 stall converter with a set of 28.5" tall tires in the rear of the truck. The trick with the setup is to find the gear ratio and tire size that gives you the best RPMs for your highway driving. With my lopey cam and the stall converter, I set mine up to run at 2500 RPMs at 75 MPH. If you have a lockup converter and not running against a stall, then you could shoot for 2000 to 2200 at 70 to 75 MPH. You can do this by changing tire sizes, easily. Just remember the taller the tire, the harder it is to accelerate from a stop. That will eat up the fuel and make you loose mileage.

You can get into a fuel injected LS motor for about $700 dollars, motor and tranny with computer and harness. The expensive comes when you try to do the harness.