Synchros are metal.....steel or brass. The input shaft should have some play in it. Before giving up on it I'd pull the side cover and have a tranny expert look at it if it is not obviously shot. I agree a good used one makes sense.

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.