No one has posted some one adding the extre O-ring to the Filter Bolt that is not supposed to have one.
Hoever, the bore a the top of the O1 Housing is tapered and is obviously allowing the O-ring to seal.

Does the Filter Bolt Head make it all the way to the top of the Filter Housing when it is tightened?

I have a few of the old housings that have that longer Filter Bolt and the single O-ring.
If a bit of air got into the top of the Fuel Filter the longer Bolt would keep the Air from being pushed into the Fuel going to the Fuel Injection Pump and there is a tiny hole at the top to bleed the air off. So in that case the longer Bolt is a good thing as it offers a better chance to get rid of Air in the Filter.

However, the opposite is true if Water got inside the Fuel Filter. With Water in the bottom the longer Bolt would allow the Water to be pusned into the Fuel Injection Pump sooner then it would with the shorter Filter bolts.

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84 300D, 82 Volvo 244Gl Diesel