On my 1980 300SD there is a metal washer that goes under the bolt head on the can type diesel fuel filter. This bolt goes in from the top, through the filter housing, and holds the filter on. This washer forms part of the seal that keeps the fuel in and seems of the copper type that should be changed with the filter. However, I've never found the correct washer, so I've been reusing the washer, together with a bit or permatex.
Just ordered online what appeared to be the correct and only part and what showed up is a rubber o-ring type washer. This doesn't appear right to me, as I would think the rubber would get squished too much when the the bolt is tightened What are others using and where do you obtain them?
TIA