We used to call these kinds of things "junkyard specials" sorry, that means all bets are off...
Seriously, my best advice is make friends with people at a good parts store. If you're in an area with a lot of ag. equipment, there will be people accustomed to finding oddball stuff. Go in there when it's slow and leave the parts behind if they get busy so they can look at it later. They will get bored eventually. We used to really appreciate that. Buy them a pizza or something if they get you something really hard to find.
Oil filter is listed as NAPA # 1324. I believe gasoline is different but IIRC many parts are the same as the 2.5. The alternator is not, I remember that and the vacuum pump is on the alternator. This is on their website BTW but only comes up under "2300 Pickup" not Mighty Max, for some reason but that's the right engine. '86 Rangers show filter 1067 for this engine they had as an option so no guarantees, ok.