727 shaft endplay

The factory service manual calls for an enormously wide range but for a performance application you want it as close to .020" as you can get it but even with the thickest #1 thrust washer a lot of the time it could be in the .030" range. If it's much more than that something's wrong.

When you checked it did you have the tailshaft securely pushed all the way forward? If it was pushed back you'll be reading the play in it also.