1999 GMC Sierra Hard shifting

The tachometer in my truck quit working a while back, and ever since the truck seems to shift hard from park to drive or reverse, as well as occasionally jerking at cruising speed. I had a buddy check the codes showing up, indicated a bad camshaft position sensor. I replaced it and it seemed to relieve some of the jerking at higher speeds, although not completely. Also, the tachometer is still inoperable & truck still shifts hard from park to drive & reverse. Any ideas? The transmission seems to be ok fluid wise & all, no leaks. I'm thinking there has to be some kind of sensor from the transmission or motor to the tach or vice versa. Any help would be appreciated!