Rear sye shaft the culprit?

I got this insane noise/vibration during hard accelerations. I could feel it in the rear when i mash the gas about half way and get the rpm's up. I been thinking it was pinion angle all this time but today I took off my front shaft and put the rear shaft up front (i have the same driveshaft front and rear with SYE). After i swapped it up front and drove in FWD (no rear shaft), it felt like it was directly underneath me. This has me thinking that the shaft is making the noise.

The noise is more of a grinding/whirring type of noise with a rhythm to it. You feel it through the cab floor whenever you push it hard. It's very low during slow accelerations.

I've always heard of the "angry sparrow" noises that occur when the double cardian cv shaft goes bad. Is this what i'm experiencing? Do they just make noises or vibration/whirring too?

I'm not 100% that it's the shaft cuz I have yet to drive it with the other driveshaft to see if it goes away but it definitely got a heckuva lot louder with the rear shaft moved up front.

Switch the shaft and go from there.

yeah I plan to tomorrow. i ran out of time today and just wanted to see what others thought it could be before i swapped em. I never thought a shaft could make such a nasty noise/vibe. It felt tight when i cycled it by hand and the u-joint at the pinion is in good shape (tom woods yellow joint).