hey guys, i need some help. i just got my motor and everything done. new cam and lifters in my 305. also new carb and fuel pump. after a few days of driving my transmission started to shift wrong. even loosing some gears. it would shift from first to drive. then shift fine. but now it shifts from first to nutral and wont shift back into first unless manually shifted to first. all my other gears are gone except 1st and reverse. any ideas what has happeened? please help