see this tip, click the pics to see detail ... I replied on your other thread, I can't imagine there's any way the speedo could affect the trans drive gear, let alone damage it, the cable spins a magnet, not much there to "freeze up" - I'd bet you'll find the speedo is either fine or stopped because it's gummed up, which won't affect anything else, but if the cable is OK, the trans problem was a trans problem and the fault of whoever put the trans together ... the same shop that's done the engine 3 times supply the trans?
Bill