I just purchased a pair of 60 lb'ers from Mike at Strut-Your-Stuff.
Excellent customer service, pretty fast shipping.
Good email skills.
One thing I would say is get the "metal" ball socket ends, instead of the "plastic" ball socket ends.
My idiot brother-in-law broke one of the "plastic" ball socket ends, so I contacted Mike, via email, and I've purchased the metal ball socket ends and they are on the way (even though I haven't seen what they actually look like).
The plastic ball socket ends may be OK if you can keep my idiot brother-in-law away from them, but they do seem to be a little weak where the keeper clips enter the plastic ball socket end.
I'll know more after I get the metal ball socket ends, in a day or two.
Another thing is that it appears that I'll be moving each of the lower ball mounts (on the camper) about 1", to make these work. The Suspa 40 lb'er ones are just a little shorter. And, if you think you know a way to compress the gas struts while hanging in the air, please let me know. At least I've got the room to move them and I'm planning on using bolts with a cap nut on the inside for the attachment, instead of the screws that were originally used that have the sharp points inside.
If these work OK on the front (haven't actually had a chance to test it yet), then I might do the same on the rear... replace the originals with stronger ones, as I'm eventually going to have about the same amount of weight that I have on the front, on the rear end (not happened yet, but soon).