I have an 2001 Silverado 1500 2wheel drive, it has a stock 4.8 liter. I recently purchased what would be an enclosed tandem 5x12 & ii gave the motor a run for its money on the hour & half interstate drive back. Alot of the problem was the rearend gears, that I will be replacing. But I was also looking for opinions on if I should do some modifications to get more torque or just by a GM crate motor. I am still upside down in this truck so trading it in on a new one is out of the question for a while. The next one will be a box truck.