need to trouble shoot trans trouble

i have a 1965 plymouth fury lll it has the 318 motor poly setup.question one need to know what tranny it has its automatic.and two first ride in car not far round block noticed it seems to start out in first skip second and go into 3rd but can't beside its third or second.car sat say 3 to 5 years as far as i know.car has red nice and clean fluid but not to take anything for granted maybe someone before me put the wrong fluid in so after reading my manual it looks like "FLUID A " is recommended for it is this right?last question where should i being to look for my problem in this tranny.one more thing the change into the third gear if it is changing into third is very hard i mean jerk you in the seat.i do not see any vacuum hoes from anywhere going to the tranny so a vacuum modulater i don't see.again i am just getting to know this car from front to back so i am not taking anything anybody did before me is right.trying me best here and asking for help thanks
Author: t65fury3