Just bouncing this off everyone to verify a hunch:
Shimano freewheels (both 1/8" and 3/32") having same issue. Under load I get a consistent 'tick tick tick tick' noise that stops when I coast.
I've examined the f'wheel off the bike and there's (what I think is) a significant amount of lateral play to the sprocket. Definitely more than when the part was new. Is this the most likely cause for this ticking noise?
Things I know it isn't: Chain, BB, pedals, cleats, hubs, chainring bolts, spokes... all the usual things one would check for with an annoying tickticktick sound.