8 3/4 transplant into my 66

Well, I took a look under the 66 tonight and measured the drive shaft.

Mine is approximately 44 7/8" center to center. So I guess I must have shortened it and forgot. I did have an 8 1/4" rear with the original 904 in it for a short time before doing the swap, maybe I used that driveshaft?

The thing I am curious about now is if it's supposed to be about 49 1/4", how is mine about 4 5/8" shorter? Is there different length tailshafts that came on the A body 727's? Maybe it's not an original Dart trans?