WHAT DRIVESHAFT!! 86 5.0ho with 60s or 70s C6

[65fordguy]

What driveshaft to get!?!!

The truck had a shaft that seems to be right length but the yoke will not go on far enough to seat correctly...it will seal the transmission to keep fluid from coming out though. It needs to go in about another inch or so to be right. could there be rust or something in there keeping it from going on??

If I take the shaft off...what can I put in to stop it from leaking 3 dollar a quart fluid.

Is there a good modern driveshaft that will work?

The truck has a 5.0 HO mated to a C6 sitting on 390 perches.
the transmission mounted right to the truck brace...where as
the 390 that was in it did not. it just was resting on the rails.

The truck had originally had a inline 6 so I feel like the drive shaft was for that.

What do you think??

[instig8r63]

Jack the rear of the truck up on wheel stands to stop the fluid from leaking out and pull the driveshaft out. Throw the old driveshaft aside. Call your local driveshaft shop, tell them your trans/rear-end combo and tell them to make you a new driveshaft. They will ask you to take a measurement (I can't remember exactly where, but I think it's from the end of the tailshaft housing on the trans to the flat part of the pinion yoke where the u-joint straps go). This way you will have a brand new, balanced driveshaft. You can get aluminum, steel, carbon-fiber, etc.