Gear Vendors over/underdrives were mentioned a couple of times in the last couple of days. I have two cents worth to offer relative to those things.

This unit is a direct descendant of the Leycock over-drive that used to be found in large numbers of MG's, Triumphs, Austin-Healys and others. It is a very simple and rugged device that shifts ratios as does one part of a hydromatic transmission (and a model "T," for that matter)--ie. a sun-and-planet system. The GV is made under license to Leycock, according to the nameplate on my OD.

I installed my OD in my back yard--the only "farmout" work was to shorten the driveshaft. It was no big deal to install but I have a fair amount of talent and wherewithal in this regard.

The PU is this case is an '89 F-250 with 4:11 rear gears, all spun by a 460.

I have been VERY pleased with the results of this installation. When one does the arithmetic, one discovers that the OD ratios neatly split the "notch" between first and second as well as between second and third in the stock C-6 transmission. Put it another way--I have SIX good and useful forward gear ratios to play with. I can find something that 's just right for any condition . . .

The competition (all that I know about) is an offering by U.S. Gear. I chose GV because the USG unit would (because of physical size) have required modifications to the exhaust system and I thought that should be unnecessary. Plus, I have had Leycock units apart and felt comfortable with the familiar aspects of the GV scheme of things.

Clark
WA7GGV
27' '70