Attention: TDR Forum Junkies 
IMHO
I have 3. 55 gears and tow many more miles than you do. Just completed a 300 mile round trip for Xmas and have 12. 7 MPG. My fiver weights less than 10K and I have a airfoil. [at least keeps the bugs off front of trailer. ]
This summer did about 5,000 miles. Had to run with O/D locked out several times just to keep RPM about the 1750 line. But interstates, no problem as long as I stay away from very hilly roads.
If free and with the amount of towing miles you do, my opinion, do the swap.
I have 3. 55 gears and tow many more miles than you do. Just completed a 300 mile round trip for Xmas and have 12. 7 MPG. My fiver weights less than 10K and I have a airfoil. [at least keeps the bugs off front of trailer. ]
This summer did about 5,000 miles. Had to run with O/D locked out several times just to keep RPM about the 1750 line. But interstates, no problem as long as I stay away from very hilly roads.
If free and with the amount of towing miles you do, my opinion, do the swap.
