Speedometer help

How do i get a 29 model a speedometer to work with a sbc350/ aluminum powerglide trans or a turbo 350 trans i might not use the powerglide but in case i do how do i make it work? Any special speedometer cable put there? This is something i havent done before. Thanks

 

most old speedometers use the same ends, Length is your only concern

 

Assuming the transmission you use has a mechanical speedo drive, getting the speedo to work is just a matter of coming up with a cable of the right length that has the right fitting at each end. Chances are there's a stock cable somewhere that'll do the job but identifying it could take a lot of searching.
The easier, if more expensive, way is to have a speedo specialist make up a custom cable for you, screw it on and you're in business.
Getting the speedo to give accurate speed and distance readings can be a little more involved. Most American speedo drives turn 1000 revs per mile and read 60 MPH at 1000 RPM. When you mix rear ends, transmissions and tyre sizes there's every chance your speedo cable will be turning too fast or too slow. You can check your speed reading against a GPS and make adjustments until you get it right. The usual way of adjusting speedo cable speed is by changing the driven gear in the transmission for one with a different number of teeth. Most transmissions have two or three alternative gears available and OEMs would install different ones according to the rear axle ratio the car had. A gear with more teeth will make your speedo read slower and fewer teeth will make it read faster. The range of adjustment by this means is pretty limited though and many combinations will require a bigger adjustment than this can give. The answer is a correction box from your friendly speedo specialist. This is a little gearbox that can be mounted on the transmission, on the speedo or anywhere along the cable. It contains interchangeable gears that can be swapped - a bit like a quick change rear end - to give a wide range of drive ratios to suit virtually any combination of speedo and transmission.

 

Here ya go -
http://tri-5.chevyrides.com/speedo.php

Cosmo