The gearbox on my 1974 3500 is a bit notchy, and recently spat out a synchro tooth when I changed the oil. As the car is my daily driver I don't want it off the road for too long so have acquired another box which I intend to have rebuilt in readiness for the current box's eventual demise. Is there anything particularly unusual or complicated about the P6 box, such that it would be wise to take it to a marque specialist, or should any competent garage be able to do it?