Tune a stock mandated 2350

[Waterloo]

I have 3:42's with an 18 speed, which makes it easy to keep the RPM in a safe range, or I would have swapped them out for say a 3:55 to 3:75. I try to stay local, Detroit area, a heavy load for me is say 15,000 pounds in a van. If I was doing what you are doing, I would be swapping out the rear end gears for something in the 3:90 range like Rawze stated. You are lucky you have not dropped a liner, you don't need tuning, you need gearing.