Driveshaft length?

That is the measurement for a 727 in a Dart isn't it?
maybe not;
my little Govier book says has no listing for a 904/8.75.
The closest thing would be a M/T and 8.75.
They have one application for 70/71 and it is 48.96
They list 7260 joints on that
But that shaft would have the large slip-yoke on it
It is pn2883760

Yup, it would be best to swap the entire driveline for the bigger stuff now.
Whatever the yoke on the rear end is match that.
Could be a 7260 or 7290 either one I think, but specs can be found for them all over the net.

Now all he has to do is pick a measurement out of the posts. :D
There's no way I would do it without my own measurements.
No offense.