Car Covers 4 Less

Hi, I own a 1992 Nisan 240SZ limited edition for over 10 years. Just this past summer I had problems lowerig my convertible top and was told it was the piston. I looked around as much as possible and couldn't find the part ( at the time the car shop took BOTH sides out so that I could temporarily lower the top manually, they suggested that I replace both sides the car is coming up on 18 years old and i had used the top in summer as much as possible) I had hopes to replace the pistons and buy a new top for the car, all to be working by spring. Can you help me?
 
I would like to know if you carry or know someone who does that has the pistons and i would like a price on a black rag top for my car, the top show signs that the frame is rubbing on the canvas so I don't know if I would need pads too ( I read up on your car parts glossary and think i may be using the right term). Also if there is a shot that you would know someone who would install it, and hopefully it isn't expensive to do so. I don't know if there are any other parts I need to consider.
 
I really appreciate any help you can provide,