Wierd shifting 200-4r, I need a trans expert!

[jroc]

I just installed a 305/200-4R combo from an 89 caprice into my 56 Chevy truck. I need help diagnosing the upshifts. Under acceleration the RPM goes up normally then jumps higher for a full second just before a normal upshift. It feels like a quick downshift then an upshift. The fluid is clean red, I adjusted the tv cable, didn't change anything. The other abnormality is the trans won't spin the speedo cable, so the vss is crippled and I had to bypass the ecm and wire the TCC to lock-up in 4th when the brake is not applied. I may have screwed this up but I don't see how. The trans came out of the donor car extra clean, with a new pan gasket so I"m guessing it's been recently rebuilt or repaired. Any insight?

 

[lowellp]

Did you change the carb? Probably has to do with the TV cable, a geometry problem. Check both of the speed-o gears, one or both maybe striped.
Thanks Lowell

 

[chris718]

What happens if you disconnect the cable,pull it all the way out and lock it with vice grip or wire tie and put it in drive and take off?does it shift before the redline?