Scott, welcome to the board!
Nice to see yet another Pacific Northwester here. There concentration of diesel owners in the Portland and Seattle areas is probably the strongest in the country... You're in good company.
It sounds like your 245 is a true 1984 model; many of the 1984-titled 240s (and some 760s) are actually more like 1985s, with a lot of little changes that make them quite different. One of the main differences is in the glow system -- the "1984.5" cars have a single 740-style glow plug relay mounted to the washer bottle under the hood, while the 1979-1984.0 cars use two relays, one of which is under the dash, like you're describing on your car. Anyway, sometimes this is something to keep in mind when ordering parts -- the split 1984 model year can occasionally make it tricky to get the right parts from Volvo, so oftentimes for early 1984 cars I have found it easier to look up parts for an '83 to be sure I'll get the right stuff.
You have already gotten a lot of good work done on the car, by the sound of it! Looking forward to hearing and seeing how the progress continues. Going through the sleuthing process, trying to figure out how the mind of a PO was wired (or IF it was wired at all!) based on the prior electrical work they have done on a car, is always fun.
If you do determine that it is due for a timing belt change, just remember that you can't rely on almost any shops, even dedicated Volvo or diesel places, to have the specific tools and knowledge for doing a D24 timing belt correctly. They're not tricky at all to change if you have the right equipment and know what you are trying to do, and are willing to take your time with it -- but they are also completely intolerant and unforgiving of cheating or mistakes! Many D24 engines have been destroyed during or shortly after timing belt replacement work in the hands of experienced, professional mechanics; it's probably the #1 or #2 cause of untimely death for them.
Portland is fortunate to be one of only perhaps three or four cities in the US where it would be possible to have the belt changed correctly at a regular shop -- I believe Kevin (member Slobodan, posts here from time to time) works at a Volvo specialty garage there. However, it sounds like you already have a lot of experience working on the 240 series in general, so if you find that it does need a belt, you might want to consider doing it yourself. We would be happy to help you with tools and information here on the forum, and there are members local to you who may also be up for helping in person.
Glad to have you aboard!