Finally got a chance to do some checking. Now another strange symptom that may imply my problem is in the column / ignition switch... I think. Turned the key to the run position (not to start) and it cranked and started right up. Freaked me out a bit, was just getting ready to crawl under to check for the noise. So it's definitely the starter cranking over when in park, now I need to isolate why...

89' v6 5-speed Raider 33's (toy)
95' LS Montero (the tow mule and workhorse)
87' 2.6 Raider (in process)
88' 2.6 Montero 2 dr (in process)
88' 2.6 Raider (organ donor)
89' 2.6 Power Ram [D50] Jr's wheels