1a. I was calling the head seal oring,
the large diameter O-ring on the inside where the steel hydraulic head
with the 4 pressure valves seals into the aluminum body.
The most nervous part for me was worrying about that shim drop,
I actually didn't even use the longer bolt offered by DG,
I just used one of the two longer bolts that attach it to keep it from coming out too far.
1b. I don't think so,
we ended up using a section of tubing and
listening to the various joints of the pump after shutdown and
could hear a slight bubbling sound almost to the head joint at the pump body.
I did change those seals as well since they came in the kit,
I wouldn't want to try and reuse them if one rubber seal had failed after that time period
i'm sure the rest weren't far behind.
The new ones were def[initely] more supple than the old ones!
3. Mine wasn't really a fuel leak that I could see,
at least not a dripping problem.
I never left any puddles.
It made it harder to find.
I suspect the former owner may have been running higher concentrations
of bio since its fairly popular here in nc,
but when i got it my usual station has only regular ulsd and maybe caused a shrinkage issue.
4. I would love to hear about it if someone knows of something,
I have several of these and many reg diesels,
now and over the years and have never had this issue before
but then again the fuels are changing pretty fast lately,
... [I'm speaking of the] advent of various bio fuels and such.
5. I wonder if the dye in off road shows up with a black light or something,
if it does, maybe feed the pump off a small tank of off road and look with the black light,
kinda like looking for a/c leaks.