77,
I think you are refering to trim tabs. Jack plates are used in outboard (eggbeater) setups between the transom and the outboard. Without seeing your hull, I would say leave them on. It costs $950 to have a diverter installed on your panther to adjust trim, and if you have plates, the previous owner may have found a reason for them. If they are adjustable from inside the boat, play with them a bit to see if you notice any speed diferences. If they are the types you have to adjust from outside the boat, do the same, but mark their original location before you start messing with them. Bottom line, try em before you junk em.
Good luck,
Chris