driveshaft leaking?

[254chamorro]

Where the drive shaft goes into transmission (84 c10 th350) red tyranny fluid is dripping from the u joint but no leak around trans seal or around the part that goes into trans. How this happen?

[jg1977c20]

if you dont have any spots further ahead that are leaking you can bet its the output shaft seal .

[skinu]

theres a hole in the end of the yoke ,you might be able to permatex it from outside but I've always had luck by taking it out ,or slipping it out of tranny and dabbing it. if theres no hole then its the end cap in that case put about twice as much as you'd use on your tooth brush if you brush on the tranny output shaft and push all the way on that should do it for your ghost leak.

[SkinnyG]

Yes, the yolk has a hole in it, right behind the u-joint.  It's made that way.

Inside the tailhousing is a cup on the tail shaft for the yolk to go into, sealed with an o-ring.  When the o-ring fails, ATF gets into the output shaft splines and leaks out the u-joint.  The hole/cup/u-joint is to allow the yolk to slide on the splines without fluid leaking.  Seal the hole in the yolk, and it will work fine.

I brazed mine closed, but I must have messed it up, so I JB Welded over top and it's been fine since.