Why would a Chevy 350 trans seem to lock up in first gear It acts like the parking brake is on?

CHECK YOUR TRANNY SHIFTER PLATE ON DRIVER SIDE PART OF THE TRANSMISSION , SEE IF IT LOOSE, THE LEVER IS CONECTED TO A BOLT THAT CONTROLS THE GEAR PISTON THAT SHIFTS GEARS , IF YOU CAN SHIFT THE GEARS BUT DONT HEAR A CLICK , THAT MEANS THE BOLT ON THE OPPOSITE SIDE OF THE SHIFTER PLATE ON THE INSIDE OF THE PAN IS LOOSE OR MAY HAVE COME OFF AND YOUR TRANNY WILL NOT SHIFT AND STAY IN PARK ......IF THAT HAPPENS , AND YOUR NOT HIP TO WORKING ON TRANNYS , BRING IT IN OR TOW IT, IF YOU DO UNDERSTAND SOMETHING ABOUT TRANNYS , DRAIN THE FLUID PULL THE PAN OFF AND YOU WILL SEE WHAT IM TALKING ABOUT ..HOPE I HELP ALITTLE IF THIS DOSENT EVEN PERTAIN TO YOUR QUESTION SORRY ABOUT WAISTIN YOUR TIME...