////////////////Anyone know where I can get my hands on a speedometer gear for
//a T-10 tranny turning a 3.31 rear-end?
//////////////////////////

Speedo driven gears for T-10's are available at your local Chevy dealer.  They 
are also the same gear that's in a Powerglide, TH350 and a host of other GM
transmissions.  The gear you need is also dependent on the height of your
tires and the number of teeth on the speedo drive gear. Plenty of web sites to
help you find the number of teeth on the driven gear you need given the
variables. 




The gears are available from any GM store for about $8.  The book even has a
chart to show what you need for most common tire sizes and rear axle ratios.
Pulling your gear to count teeth is easy.  If you are 14% slow, you want a
driven gear with fewer teeth.  If 14% fast, a gear with more teeth.

thnx, jv.