OK, looks like you're overweight if you have the lesser engine, and marginal with the better one. If you call a Toyota dealer with your VIN, they will be able to tell you which drivetrain setup you have.
Now...let's complicate it a bit more, shall we? Will you be towing in mostly flat lands, or will you be towing in the Mountain West?
Dry weights are essentially meaningless....they often don't even include things like the A/C unit on the trailer, propane bottles, etc. Gross weights can be deceiving too, as some trailers have carrying capacity you'll never use. That said, Gross weight is the safest number to go by. Remember that the truck's tow rating has to be reduced by any additional passengers beyond one 154 lbs driver, any cargo or luggage, and even the weight of the hitch assembly. You also need to discount 10-20% off the tow rating if you tow out here in the high country.
Give the dealer a ring and see which drivetrain you have first, and then decide from there.