Seen a number of them in otherwise untouched cars - majority or all from eastern factories. See's that either Ford didn't provide very tight/specific engineering requirements or had a supply problems - using these as a filler. Never found a part or engineering number on one nor packaged as a service replacement. Have seen one or two in a very dark - almost black color also (recall in a 68 Shelby conv at Mid America and SAAC a few years back
Just a guess at this point