I have a 1999 F250 Super Duty 5.4L, 3.73 geared Supercab.
I will be pulling a 8000lb 5th wheel trailer. Most of the time on flat ground, but a little in the East Coast mountains.
Should I go to 4.10 gears or put my money in chips and such..

 

I would suggest going to the source on this one. Post this same question to Mike Troyer on the Computer Chips board.

He'll be able to explain exactly what the chip or tuner will do -vs- the gear change. The guy is very sharp and knows his stuff.

I've installed the chip and am very happy with it. Have not done any gear change so I can't give you any comparisons there...sorry.

Good luck...