I know this was covered a little over a year ago and maybe again since then but this perhaps maybe of use to someone. I could not reply to the other thread because it was over 500+ days old the system said.
Anyway, my engine compartment door was dropping down and the struts had PN SPD-GS-5150-80 on the original ones.
I decide to change the struts because after lubing the hinges recently the door kept dropping down. My first mistake was fixing something that wasn't broken, I know! But I decided the 20 yr old struts were ready for replacement. I ordered off Ebay here: https://www.ebay.com/itm/392285441933
Once here to install I had to compress the little rascals, which I could barely do outside the rig on the floor and no way could do inside the compartment. To overcome that problem I threaded a strong but small string thru the eyelets and compressed the units in a pole clamp to about 11.5" (ball socket to ball socket) and tied the string as tight as I could. Once the pole clamp's pressure was removed the unit expanded to around 13.75". Not far off so I could wrestle it into place. As a side note, I moved the spring steel clamps slightly, that hold the ball joint in, out of their slots to allow room for the string and ease of getting the ball joint on the ball in the confined area. After getting the units in place, I cut the string and remove it and then pushed the spring steel retainers back into place.
Now the door stays up with a bit more authority or spring pressure but not so much as to be excessive.