Rear Hatch shock pistons

Hi, I got a 94 astro with the 3 door rear hatch and the pistons that hold the large top door open ,well, they don't anymore, especially bad in cold weather. . Anybody have any luck in changing them out? Any good how to's out there? How about where to get some replacements?
Thanks for any help, John

Those should come out by using a flat screwdriver. There is a metal clip on each connection that you pull up and then pull them out. I would assume car parts place might carry them because they are common to other vans too.