I'll bet that they are most likely mono-tube gas charged. Those can be mounted in any position because there is no air space in the working area of the shock. The oil doesn't foam and reduce the effectiveness of the shock, either.

I'll bet they were pricey, too. I'm leaning toward mono-tubes on my project. After watching a couple of videos, it's not hard to see the improvement.

Here's a video if anyone is interested:

https://www.kyb.com/kyb-tv/the-diffe...n-tube-shocks/