im looking into picking up a 1981 Scrambler...it has 49k original miles w/the straight 6...has 6" lift w/35s...full doors,full top..good body and interior..they said the only problem is that it doesnt want to go into reverse w/out a lot of grinding..(manual tranny)..but every other gear works fine..now does this mean it needs a new: synchro,clutch, or total tranny rebuild..?also how much would you think it is worth..?thanks for any help..