You'll need a rebuilt transmission, whether you have your current one rebuilt or buy a rebuilt one. If you've got a knack for mechanics and attention to detail, you could try rebuilding it yourself. It's recommended to replace or have the torque converter refreshed when the transmission dies. Not gonna lie, it's a LOT of work the first time and you have to do a really good job so that it both works right and doesn't break month later.
Why not just replace the clutch pack? The vast majority of the cost of a rebuild is labor. If you are doing or paying for the labor, you'll address other things while you have it open i.e. rebuild kit with all the clutches, seals, etc. If the 3-4 clutch died there's probably something else that needs looking at, like the 3-4 piston.