This is what I've been told
"Yah, 5.3 isn't really a towing motor either, but at least it would have enough to be able to drive the truck relatively normally. Not with the 400 and factory taller gears tho. You would still need short gears. Pretty much nothing ls-based is going to like the 400 and tall gears. A 400 is usually set up from the factory to upshift around 35-3800rpm, and at 4000, even with the shifter pulled down to 1st, it will automatically force an upshift (and a violent one, at that) to second gear. Now in most cases, LS engines are just getting into their power band at that rpm (including the 6.0), so the 400 is a total waste of LS power. You are doing an LS swap just to be able to fit in with the 'in' crowd and say that your truck has an LS swap. But you aren't thinking about what all needs to be changed to make it work in that truck. You are trying to get away with cheaping out and doing a bare minimum, when that isn't going to work for that truck the way it's currently set up. The little LS engines are not designed to be heavy truck motors, and you will have nothing but problems if you carry on with the way you have planned this swap. So either bite the bullet and build the truck properly, or give up on the LS and just build up a good RV 350 for it instead. It would work way (!!!) Better than those little underpowered screamer LS engines"
