Hello everyone,
Let me backup a little and start again. I joined this forum a month or so ago - I bought a 1946 D6 5R kind of on a whim. LOTS of you have immeasurable knowledge about these older - and newer - machines. I knew this would be an invaluable source of info, etc. and it is. I've already gotten needed parts from another member as I had hoped, I can't thank them enough. I originally asked a couple questions or so on my very first post and was answered quickly (thanks to all again). I'll still need much more advice, etc. about this adventure (dozer doesn't run yet, several issues to overcome) but it's fun to learn the basics anyway. I've owned lots of old tractors like some of you guys ,mostly John Deere's and Farmall's. Some things carry over and apply to tractors and dozers alike, sometimes things are completely foreign, to me anyway. 
So.....another question I have is the "ferrule" part number 2A3855 on the fuel filter tower needs part number 8B4967 pictured on the injection pump to seal. An internet search shows the part as a round rubber ring but, I don't see how it would seal as the injection pump housing where the ferrule on the filter housing mates to is concave/sunken in. Can anyone verify this would be the correct part number and shape? My old seal (tapered, conforms to the injection housing casting) most likely is bad as the oil is quite diluted from diesel seeping back through it into the oil pan. I'm putting new seals, gaskets, etc. on the fuel filter, injection pump and governor and would like to get it right the first time.

On a side note, I live about 90 miles away from Peoria, Il. where most of these great old machines were made. I've driven by their headquarters dozens and dozens of times over the years. I appreciate any advice on the seal question. Thanks!

 

That seal is in fact a dash-318 o-ring that takes on the tapered shape over time. Replace the one on the rear of the injection pump when your in there, same seal.

Thanks oldmagnet. I wondered if the ring would become flattened/compressed over time distorting it's original shape.

Kurt, Once I get it running I'm sure it'll be a blast. Thanks.

oldmagnet:
I can't find the part number for the o-ring. Is  -318  the part number? I have a 1946 D6 5R with the 4600 engine if that helps. According to my original 5R parts catalog the seal number is 8B4967 - online pics show a very small diameter o-ring looking way too undersized to seal. Hmmmm. Thanks.

318 is the standard trade number for the o-ring . Any hydraulic shop or industrial supply would have it.

I believe the Cat number for that O ring is: 8B4967

Just ordered 2 off the internet. Thanks for verifying.