Dump the plats and get some regular old copper core Bosch plugs, the non resistor type. I think you need W9DC plugs. Working from memory on this one, but should be close.
'73 280SEL 4.5 (9/72)- RIP
Only 8,173 units built from 5/71 thru 11/72
'02 CLK320 Cabriolet - wifey's mid-life crisis
2012 VW Jetta Sportwagon TDI...at least its a diesel
Non illegitemae carborundum.