Its been awhile since I've posted anything I didn't have a Buick for 10 years or so. I recently picked up a great 1971 Skylark custom convertible and the speedometer needs to be slowed way down. The previous owner recently installed a 3.42 posi from an open 2.56. BOP TH350 Axle ratio 3.42 Tire size 27inch Drive gear green 15 Driven gear red 37 I've read other posts and looks like I need a 42 tooth green gear and a new housing that fits it, although I just looked at the TCI calculator site and it says I need a 38 driven gear. Not sure if that TCI calculator works for TH350 BPO... Anyone have some sage advice? Here's a pic of the car for fun
Yup, that is correct, https://www.amazon.com/Speedometer-Gear-1359272-Tooth-Driven/dp/B00P8BKOES Your current sleeve should take the 38 tooth gear. I think they are 34-39 .
