73 Dart Sport Driveshaft length?

Car has a vibration at 45 mph in 3rd, downshift to 2nd goes away. New motor and tranny mounts, new rear spring bushings, new u joints, rims are straight.

I'm pulling the tailshaft to replace the rear bushing. Driveshaft in the car is 45" C to C. The yoke does have up and down play.

I measured shoving yoke forward, pulling back 3/4" and I need 46"

Anyone have a stock driveshaft they can measure? All the charts don't list a 340/727/8.25 that I've found.