Believe I found it!
For whatever reason the outer most "dust shields" of my CV axles are now barely kissing either my new spindles and/or uniball dust caps (which were installed with the wheel bearings/spindles) - and only on one side each, which is probably why I'm hearing it wub-wub-wub in the corners. I went to rotate my tires today and didn't notice until after I already put everything together and put my jacks away, so I'll give it another whirl tomorrow. The way I see it these aren't totally necessary on our vehicle as they're not really blocking anything on the hub side (which is fully sealed anyways) nor sealing the axle at all, and they can be easily popped off with a hammer. But right now it's 84* and 50% humidity right now so that's enough for today

Aftermarket cv Axles don't have those dust shields. If they are too rusty or hitting things. Might have to knock them out. :]

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Good to know! I was gonna remove them but I saw there was a rubber seal on the inside, and even though it just looks like a secondary seal for the wheel hub (or at most, helping keep the axle snout dry), I decided to leave it in and try to hammer them down a little bit with a brass punch. The noise definitely changed but isn't gone completely so maybe removing them altogether is the way to go
Edit: on further investigation supposedly they' pretty pertinent to keeping water out of the bearing? Or at least according to Taco World? That seems weird to me if OEM axles are the only ones with them...