Here's the part number and descript for the trans kit from summit.
Rebuild your transmission before it's too late.
Ford: 1977-up C-6, pro super kit
The TCI Pro Super Kit has everything to do a complete rebuild: gasket and seal kit, reuseable Duraprene pan gasket, high quality clutches (including extras to make your transmission shift harder), bands, adjustable modulators, high volume filter, and a drain plug kit. TCI didn't include instructions, so if you're new to transmission work, we recommend that you take it to a pro to have it installed.
Sold as a kit. 184.95
I had this very thing saved in the my garage area.
If you're going to rebuild and beat it like a rented mule, then make sure it can take it.