I own a 1993 Mustang GT and i just put in some gears (Richmond 3.73's) and I think i have a problem.
I picked up the car to what the spedo read 125 MPH. (I am not sure what i was really doing but that is what it read) And my Pro 5.0 shifter and what felt like my clutch started to buzz/vibrate. Is that normal? and stoped when the speedo read around 90 MPH.
Any idea how off the speedo is. I am also running 295/50 15 tires out back.

 

there is a speedo gear in your tranny you have to change when changing your rear gears

 

Is that what is causing the buzzing?

 

any one?[&:]

 

Well, if it didn't do it before the gear swap, I would say they did something wrong. Take it back to the installer and let them know.