Ford 9inch to 727 driveshaft

If its a 1310 u joint you will need an adapter U joint plus a ford 1310 u joint
for the wider yoke ends
NEAPCO 2-3100 Dodge 7260 series Mopar to 1310 series combination universal joint.

Neapco 1-4635 Greaseable Universal Joint 1974 to 1978 Ford Mustang II - use at rear end of driveshaft
Also the 9" has 2 different yoke lengths so you may have to shorten/lenghthen drive shaft accordingly if so do what Dana said