Yeah, I've found the 342s really keep the revs down on the highway, and increase my around town MPG. But they're not for everybody.

 

What about an 01 silvarado 4.3 5spd 4X4? Not sure about the gear ratio, but i figured the 5spd might help a bit...

 

While on the subject of fuel economy, I’ll weigh in with my 2cents. With all the claimed ‘fuel savers’ out there, I found 1 that was cheap & worked. A trip form Tulsa to Dallas, I used to run thru about ¾ of a tank each way. Now it takes a little less than ½ a tank. The only thing different was the Lucas upper cylinder lubricant in 2 tanks of fuel. No fancy chips or mods, just a 32 oz bottle for $10 at the auto store – enough for 2 tanks in each truck and the cobalt. That with regular oil & fluid changes- they are all running further, soother and about 5MPG higher. Everyone has opinions. That’s what happened to my 3 Chevy’s. It’s a mildly hilly drive in spots. I drive with my cruse at 60 to 70 (75 on the turnpike.) Different cars, speeds, terrain and driving styles may have different results. I didn’t do any lab tests LOL.