No, I just used 5/8-11 UNC grade B7 threaded rod. The ACME threads would be a good idea for one that would see frequent use. I don't plan on using mine more than a few times. It has minimal side loads as the shock mount rotates as the spring is compressed, and the thrust bearing is thick enough that it will not slip into the threads on the rod. The other modification I did with mine was to use a piece of 1/2" thick steel bar stock for the bottom mount, and thread it and use two set screws to keep the rod from rotating. The bar stock was something that had been floating around in my metal junk box for years and is a very good quality steel. This eliminated the stress to the rod that would be caused by welding it to a piece of square tubing. And, I already had a 5/8-11 tap.
Hope you're still following this. Th springs are not the original. I replaced them back in the mid 80's. So no markings. I think I also mentioned I have been arguing with CJ Pony Parts on the idler arm. In the kit, they sent me the wrong one, a two piece. It took up until last week when they finally agreed they were selling the wrong one for our '71 - '73 mustangs. They sent me the correct one!!
