I recently purchased a '91 GMC 1 ton crew cab truck to pull our 22' Fifth Wheel trailer with the whole family in the truck. 350 automatic 3 speed plus overdrive. Its a good solution, except for the fuel consumption! The computer must have 'moods', because sometimes its fairly fuel efficient , and just plain awful at other times - under the same driving conditions.
My first observation is that this transmission really likes to keep the motor spinning, and a 350 is a lot of motor to spin. I'll install a tach sometime to get some factual information.
We are planning to manufacture our own dual exhaust conversion by cutting and blocking the crossover and going to the back with another custom made 3" exhaust system (catalytic converter and muffler, etc).
A friend has 'almost' persuaded me to remove the manifold and throttle body and replace it with a 4 barrel carburetor. This almost seems sensible to me, but I would like some confirmation from this group. Would the right carburetor increase the performance and fuel economy, or should I stay with the throttle body?