Portaflex shock mounts
The shock mounts that Ampeg used to use were manufactured by Lord (they are referred to as “plateform mounts” in Lord’s literature). The model that Ampeg used was 100PDL-8. Lord’s product literature has not included this part number for several years, but it is still produced. If you are not wanting to buy in quantity it’s much easier to just get them from Fliptops.net. I believe they are also available from Vintage Amp Restoration, but I haven’t confirmed that.
Another option is to get something similar from McMaster-Carr. They carry a similar model shock mount from Lord, p/n 6008K61. This is Lord’s model 100PL-8. The only difference between it and the mount that Ampeg used is that it has a square base rather than the diamond base. They can be used just as they are, or you can file/grind down 2 of the corners to make them look like the originals. I haven’t tried this yet but it should not be too difficult since the base is aluminum.
Shock mount comparison
There is a manufacturing date code stamped on the metal plates. This can be useful for establishing the manufacturing date of an amp.