You can go up 4.10's using OEM gears,but if you're truck is a regular cab shortbox with the 8 speed,you'll be limited to about 95 to maybe a 100 mph with the 4.10's ,before you have driveshaft problems,about 105 mph seems to be the safe limit with 3.92's and the stock driveshaft.I'd lay odds that a light weight Tradesman with no options and 3.21's on decent 17" tires ,will be as fast if not faster through the 1/4 then the heavier R/T with 3.92's and it's 22" wheels.If you have one of the rcsb Tradesman trucks with 3.21's and the 8 speed,i wouldn't be in a big rush to swap in 3.92's or 4.10's,that'd be the last of my mods,lol.