I had one on the '32 roadster in my gallery. Rode very nice and from a driveability standpoint no noticeable difference. Would have to admit I didn't have that many miles on it to test any durability concerns. I've seen some of those comments about breakage, if I recall it's usually at one of the ends. Is it a fault of the spring or installation? Would adjustable perches make a difference or not? I don't know.

I've seen that Speedway offers one now, and it's less expensive than from Durant. Is he reselling the Durant, or did he go into production of his own? Probably worth a call. If I were you I'd call Durant and ask them about the failure issues on the web, I'd bet they've got an answer, just that you'd need to evaluate whether it's a plausible answer or not. Same for Speedway tech dept. they may have an opinion on whether it's related to perch or something else.

Also, a buddy of mine had one on the rear of a '40 sedan and didn't like the ride, he felt it was too soft. I only had it on the front.