tom29

hey guys i got my other rear end put in last week with the 3.73's. i did have 2.73's in and i was just wondering what speedo gear i would switch out if i can just change the gear and not the whole cable. car has AOD with 3.73 rear. im pretty sure its just a color coded gear..

thanks guys any info appreciated

nyfreakinrican7

21 tooth gear $10.95 part #lrs-17271G from Late Model Restoration

tom29

ok thanks ill probably just get it from my buddies tranny shop.

stang8689

Real easy to install

bighungrymatt

red 21 tooth, and yes its one of the easiest things to install

nitrous_bob

all these answers are wrong so far.

first off, aod and t5 gears are different color coded as they have a different pitch

the purple 21t gear for the aod is good for 3.27's, not 3.73's

the aod cannot swap out the drive gear, it is fixed 8t machined on the shaft

so basically w/ a ford driven gear you can do the 21t purple and be about 12-15% off, or get the white 23t (it's a jeep part and wrong pitch for any ford trans)which will wear out eventually....5k-10k miles usually on aod cars and you will be 6-8% off still and have to replace it whenever it wears out

you have no fix, other than get a calibration box, i'm quite sure they are big $$ though

if you tear your trans apart and can find a 7t output shaft , then a 21t would make it good

bighungrymatt

good eye, I didnt even catch it was an aod [&:]