i have a 1983 c6 transmission 3 speed.. shifts into 2nd at 15 mph 2,000rpm and shifts into the last gear at 30 mph at 2,200 rpm.. why r they so short can i change it and does the vaccuum modulator have somthing to do with it

 

I thought that the shift point is modulated by the engine
vacuum. So if you are stepping hard on the gas the
shifts will move way up the RPM range.

 

yeah that transmission runs off vacuum, the more gas you give it the higher the shift rpm. basically it's a 3 speed and it's going to shift early. i had a C4 in my 66 stang and that is about where it would shift if you were just driving normal.