Flat towing 65 Barracuda

If he has the trunion shaft, it has bolts in the front by the transmission also....

The early transmissions did not have the slip yoke at the back of the trans like the later models did.

Exactly, and it's a lot easier to undo the rear of the driveline and tie it up leaving the front connected to the trans even if it has the slip style yoke.
You don't have to mess with fluid this way either.