speed 6351 - sorry, i do not know about the milage. i have not run my truck that much yet. i use 3:08 rearend so i do not think it is too economic with the gas. but if you have the engine in almost stock condition and use 2:75 or 2:56 i think it would be fairly good. and there is some overdrive solutions you could use.
by the way, i should be concerned about the milage, here in sweden the gas price is about 50% higher.
64CHEVYREBEL - as i said if you want more than 500 hp go with the chevy bb. if you want to be different use a big cad and get a lots of low rpm torque.
/anders
