84 T/A 305 21000 miles -
UPDATE - EUREKA --- I readjusted the tv cable & now the tranny works! What a relief!!
ignore the info below..

Before parking the car in early December, tranny shifted fine although I had the quick shift 1-2-3 so I usually shifted it manually.. Car not not driven but back out of the garage occasionally. I had the air breather at a body shop having it restored. Today, I picked up the breather today & installed. Started the car, backed out onto the road & proceed ahead. The engine revved and when the tranny shifted into 2nd it shifted way too hard. Would not shift into 3rd unless I drove well over 40 mph if it shifted into 3rd. if I let off on the throttle, it dropped into 2nd & then I had to drive way too fast for shift into 3rd? the tv cable is adjusted as per the book. Could I be a victim of the 3-4 cluster failure?
Suggestions.

 

Glad you figured it out.
I always readjust my cable after removing the throttle body.