Its not the TV cable, its something IN the transmission. The 8 month old TV cable is completely adjusted 100% correctly as are all the other cables to the TB. What controls the 2-3 shift in this thing? I've heard it could be a valve or governor or weights on the governor. By not shifting at WOT from 2-3, its over 6k rpms and its not shifting. Any tranny builders chiming in would be nice. Im dying to take this thing to the track, but I'm not going to get any good good times if I can't shift into 3rd. Im about to buy a reman'ed 700r4 unless I can replace the part. $400 seems like a good bargain for not having this problem again.

try another valve body. make sure it has the necessary check balls.

cant be the govenor weights... if they werent working then your 1-2 shift would never come in... changing the goveneor weights will change the shift points of all the shifts and not just one shift.

does it shift into 3rd at part throttle? maybe u have lack of line pressure to engage the 3rd gear at higher rpms. i would have to assume its VB related. checkballs, or a blocked passage in the VB perhaps.

what mods have been done to this trans?

The 3-4 clutch pack might be going away. This is very common. It nothing to do with the valve body. If it is only the 2-3 WOT that is not happening, then the 3-4 clutches might still in good shape. You could try adding a Corvette servo, .500" main boost valve, .296"intermediate/reverse boost valve, and a TransGo "modified" TransGo Shift kit. This will give you the best chance at making the 3-4 WOT shift. And you would have this for the rebuild in the future if necessary.