I've made sure the t.v. cable is properly adjusted and i replaced both trans mount and u joints. The shifting at low speed is extremely harsh. Whether it's upshifting or downshifting it clunks pretty hard. I've also checked the torque arm clamp and anything else underneath the car. It is definately the trans, before and after it was rebuilt. I'm new to chevy from mopar and i've never driven a 700r4 until this car. Is that normal for these transmissions?

 

Do you Have a shift kit installed? I have a S-10 350 that I've had a few different 700's in and usually any shift kit will come with a stronger pump bypass spring which increases valve body pressure to tighten up the clamp pressure on the bands & clutch packs resulting in a harsher shift. I had that trouble with my current trans until I put a TCI 11" 2500 stall converter in. It loosened up the harshness and gave me a lot better launch.
You might be able to loosen up your tv cable to produce a more acceptable shift. Another thing to look at here it the distance from the cable attachment to the centerline of the throttle shaft. The longer this distance is, the more cable takeup it will have when you rotate the throttle.

 

mine does the same thing, what helps is having that stall converter. but i dont use one. its defiantly the shift kit. i wouldnt change the tv cable. best thing to do, is upgrade every rear bushing, the tranny bushing and torque arm bushing all with polyurethane instead of going clunk it will chirp the tires on the spot. and to keep the tire from being chirped while shifting into drive or reverse is to perform maintenance on the brakes in the rear..

Mine and a lot of other people have a bad crush sleeve in the rear differential.
theres mods to replace the crush sleeve with a solid one, and re-enforcing the rear diff cover to handle the torque. It might be worth the time, but try and see if there is any play in the rear diff, maybe removing the drive-shaft and pushing the rear diff's yokes in and out.