After about 30 mph i get a very bad vibration

Hi. Thanks for your question. ation of t/m module is related to smooth translation of gears. However for better clarification you can visit https://www.reliable-store.com and download the entire workshop manual. It has all the information along with the diagrams for better understanding. Good day!

Indicative of a bad tire or wheel out of balance. Take to a tire shop and have checked.

Could it be the odometer cable? Does the speed dial pointer vibrate?

possibly need to be balanced or check your hub bearings.

mine gets like that when its low on fluid

SOUNDS LIKE A BAD SPEEDOMETER if you can use an OBDII while driving and look for DTC output from speed sensor. possible loose connection can cause this as well

bent tyre or dish rim, check tyres and rims and speed balance would help.

Sounds like a bad thermostat.