Driveshaft fell off

Hello all,

Back again,

So Was driving down the interstate, and the driveshaft fell off to where its connected to the rearend, lately was alot of shaking and vibrating going on, the front end is now dead on, but ya the driveshaft fell off connecting to the rear end, any ideas on what wrong, I will post some pics in the morning, Car is a 75 Dodge Dart 2 door custom hardtop, slant 6 904 torqueflite, car has always been a champ. any idea's,
MOPAR 4 LIFE