99 chevy silverado 2500 5.7 reg cab 3/4 ton long bed 4x4

Just use it. The truck is more than capable. The chassis will be fine, you will be in the slow lane traveling at 50-65 mph. The little small block will have to rev... Just make sure those intake seals are replaced, leaky Vortec 5.7 intake seals kills small block Chevys. Oh, I'd also make sure you have more than enough transmission coolers if it's an auto.

Thanks!

Jeremiah