later MK1 clippers after 84ish have the sliders on the wrong side as you have found out! Have a look at the seatbelt clips too, these will also be different. If you are lucky you can unbolt the rear legs and swap em over, but I dont think you can!
If the seats dont have height adjustment its relatively easy to swap the forweard/back handle over, if they do then you cant
Last option is you might possibly be able to swap the foam/fabric base & uprights from the cabby seats onto your old MK1 frames, not 100% sure on that one.
Oh very last option is to cut off the front seat mounting brackets off the floor pan, and swap them over, this will allow you to use MK2 Golf and late cabby seats without modification. Bit drastic though!
You can still slide the seats by pulling the pin across manually, how often do you need to move your seats about anyway?
