5.3 or 6.0 in my 1970?

[texanidiot25]

Originally Posted by boostat4500

I'll chime in on the gas mileage thing just for reference. My last tank was about 60% highway at about 70-75mph. I got about 13.5 mpg. This is with the 6.0L, 38x15.50 tires, and 5.13 gears in a heavy ass Suburban. I gained about 2 mpg with the 5.13's vs 4.10's that I used to have. I would highly recomend the 6.0 over the 5.3, so much more potential for cheap.

Did you switch to the 5.13s after the tires? In theory, lower the rear end ratio allows for better MPG, lower cruising speed. But of course, on larger tires and the stock ratio the engine could be killin MPG to spin the larger tires.