6" RCX lift problems . Help please

I have a 1999 tahoe 2 door that I put a 6" rough country lift on and it already has a 2" body lift . The lift went on great but after the install I test drove it and pulled it back In my shop and noticed a trail of transmission fluid . I looked underneath and it looked like the drive shaft is at to much of an angle and the slip yoke seal is leaking and the slip yoke looks like it's about to fall out . I don't want to spend 400.00 on a special drive shaft and rough country said nothing about having to buy a drive shaft . So ease tell me what I could or should do .

If you do a 6" suspension you need to have the driveshaft reworked for that or purchase another one for the lift allowance. You have a shaft wobbling at the seal and causing the leak. Bite the bullet and fix it right with new seal and shaft work.

Longer slip yoke

Could I just get a longer slip yoke ? Wouldn't that be the same thing

I don't think there is such a thing as a longer slip yoke. The shaft needs reworked. Companies that sell these lift kits may not tell you everything you need to do because then you may not buy the kit because of the added expense. Welcome to the world of bolt it on and see what else is needed afterwards.