My 2004 neon r/t is a 5spd but my transmission has started acting up. It won't stay in 4th gear when i put it in it pops right back out and now it won't let me go into 5th or reverse gear at all does anyone know how to fix this with buying a new transmission.

Also does anyone know the difference in the transmission numbers 4668980, 5273250AB, and 5273250AC besides pricing are these interchangeable to eachother since they are all classified as a T350.