I have them(repo perches) on my 67 big block car-3years and 66 convertible-2years, have put a few miles on them and had no problem or noises.Bought one set from Laurel Mountain who I believe use Canadian Mustang parts and the other set from Keystone Mustang one year at Carlisle on special.I can't complain-at least yet.The last Ford ones I bought for my 66 GT were missing some of the rubber pieces glued to the top that sat under spring-I payed something like $45 a piece for those about 12-15 years ago.
1967 S code GT Deluxe Coupe 65B
1966 Convertible 76B 289 4 speed
Descendent of Francois Seguin dit Laderoute,
Soldier Regiment d' Carignan, New France 1665-1668