Manual overdrive Possible?

Is it possible to have a manual Transmission, but have it set up in gearing to be like an overdrive such as 700r4? If it is, what needs to be done, or what kind of trannys are out there that are good ones to use? Would you use a 4 speed or 5 speed or what? Any ideas. My rear diff has 3.73's so with an OD tranny would be the IDEAL setup. But I have a 4 manual that sucks...