Re: towing with chevy 4.8
You need to check for specific ratings on that vehicle (check the driver door jamb sticker), but it is highly unlikely that a V8 pickup truck w/ auto trans and 4wd would have a tow rating below 5000 lbs.
Don't forget to add in junk and fuel, plus trailer, into the total.
Check the door jamb on drivers side for this: GVWR and tell us what that number is.
Tow ratings are affected by trans type, frame strength, brake equipment, tire/wheel size, rear axle ratio (higher numerically tows more than the lower numeric counterparts, because these higher numeric gears are "shorter" gears) and other factors.
Always...ALWAYS get a Heavy Duty trans cooler. ALWAYS!
re: gear ratios If two trucks are equipped identically, and the only difference is that one has a 3.55 rear gear and the other has a 3.96 rear, the 3.96 is going to have a tow rating at least a few hundred pounds more than the 3.55, and it could be even more than few hundred pounds. For example, a 12-speed bike has 1st as it 'shortest' gear in the rear, but it is the highest numerically. It's the "easiest" gear on your engine/legs.