Gear Vendors Overdrive
 

Has anybody out there used one of these or something like it? I'm try to figure if the 3 to 4 thousand dollars is worth the benefits.

Do You Have A Link Or Description?

It's an auxillary overdrive that if I'm not mistaken connects to the back of your transmission. Basically works like a 2spd rearend like you see on some old farm trucks.

http://gearvendors.com/dmanual.html3
That page should give you a better idea.