[Lamonte_1993]

is the stock 85 mph speedometer have the same sixe spline where it plugs into the tranny for a automatic and a manual, i swaped mine over to a manual and i dont thin k my speedometer is working right now

[NavySVO]

The speedometer and cable are the same. The gear that drives it in the trans is different and is what is causing the disparity.

[b_chandler]

The tip that protrudes from the end of the gear is longer for automatics than than it is for manuals. Correct replacements are easily found and a better (although not cheaper) than modifying the existing gear.

[Lamonte_1993]

how do you change it out

[b_chandler]

There's a metal clip to pry out at the base of the gear.