Tranny case cracked

[MWbirdLOVER70]

Well, if you shift manually, shift points won't be affected because most who do shift manually is well past what the kickdown lever allows. IE, above what the KD will do if that makes sense....

I get that but still travels to and from the carb stud so as you accelerate more it’s moving or decreasing speed and increase or decreases if that makes sense

 

[Cranky]

li do the same with my automatic but KD is still hooked up and travels with the carburetor movement ( forward/backwards ) so maybe his is disconnected down below and never noticed on top side. KD linkage is operated off carb stud and travels via the rod ball crank another swivel point and another rod on the transmission. So shifting auto or manual it’s still moving because of carb accel/de eel but all drpendent on the linkage being hooked up. No linkage no travel no increase or decrease in line pressure which eventually destroys transmission

If the transmission KD lever isn't moving at all, the trans will shift into 2nd way too soon.....and that is a tell tail sign something isn't right and time to start looking things over.

 

[oldkimmer]

Heck the bushing in the tail housing. It was probably worn causing the yoke to be sloppy in there. Kim

 

[dvw]

Every broken tail shaft I've seen has been drive shaft related. Out of balance, broken U joint, shaft too short, shaft too long, wrong pinion angle. I've repaired two that actually bent the output shaft at about a 20 degree angle. Both required floor board repair.
Doug

 

[QuickBpBp]

The input shaft is sticking pretty far OUT of the tail shaft. They make 2 different ones a long one and a shorter one. This one looks like it’s barely in and if it’s the shorter version that could have been the issue. Start with the correct length driveshaft and then also check pinion angle…

 

[65CopCar]

Mine was caused by improper rear u joint installation. First pass down the track after assembly it let go. Some dumbass (me) didn't install the joint correctly.

 

[Sparky Anderson]

Everyone may be correct, but also your transmission may of been damaged from handling before installing, with a hairline Crack and might of just let go finally.
It has happened to me, I replaced the tail housing in car 10 years ago and still working great.