Maybe someone makes a taller gear to replace the stock 5th. Wouldn't take much to make a difference. Somebody here must know what all the different ratios are in all the Nissan manual trannys. Maybe something from a Frontier? There has to be some parts interchange-ability in all those trannys out there. Sounds like a good idea to me. When I swapped the stock trans out of my Merkur and put in a T-5 from a Mustang I went from a .80 overdrive to a .65 in 5th. There's a 1000RPM gap between 4th and 5th now but it's a great highway gear.