c-4 problems

ok so a few happy days of driving my car, and my 3rd gear just went out on my c-4.... i got one i've got already torn apart but its gonna be a few weeks til i get it together.... any chance any of you guys know how i can lockout 3rd gear so i can at least do around town driving for getting to and from work...its a 66 mustang, 302, with a greendot c-4, originally equiped as a six cylinder unit

well i figured it out... i talked to a reputable transmission guy, he said generally on c-4s when that happens its the high end clutch pack that goes out... so it looks like i'm gonna have to finish rebuilding that other tranny to get my car up and running again