Hi Ho: I found physically identical replacements for my coach at Auto Zone. They stocked only 2, so I made several stops (right on my way home). They were about half as much as the lifts from WI suppliers. Also, if you spend $20 or more they give you a $20 credit after five times. This is effectively a 20% discount.
Also, I found that I needed to replace only one on each door to hold the door open. They still work fine after 3 years. I guess some of us as just cheap.