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Sounds like whoever installed the Gears, didn't do a good job, maybe get another set and try a new shop.

You're not getting that noise from Poly Bushings. IMO

 

I thought the same thing but going from 3:31 to 3:73 and pinion angle being corrected and all the adjustments that need to be made I doubt it's out of whack. The guy who did them has a lot of experience.

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I suspect the majority of your noise is coming from your aftermarket UCA. Robert did a nice write up on different UCAs and I if I recall correctly, the OEM Ford unit from 2011+ was a good option to increase stability without the noise of aftermarket units.

Edit: I was typing when JTB replied. I’d still look at your UCA before tackling another gear change.

 

I understand that Roush has a upper control arm that does not make noise and would be better than going to stock if that is the issue.

 

Poly bushing could tend to amplify the noise, but it's not the cause of the noise. Then again, we're not hearing what you're hearing. I have 3.73s and poly bushing on every joint in my rear end and I don't hear anything objectionable, but my hearing isn't worth much either.

 

I’ll add this too... I hear “whirring” noises too, but my sound is not from gears. I have stock gears and a stock UCA. I have Bob’s LCAs with poly bushings as well as a Fays 2 Watts Link. My whirring started as soon as I installed my noisy-ass Toyo R888s. The noise they generate comes up through my watts link, but it is acceptable to me for the improved traction.

So, do you have noisy tires?

 

I’ll add this too... I hear “whirring” noises too, but my sound is not from gears. I have stock gears and a stock UCA. I have Bob’s LCAs with poly bushings as well as a Fays 2 Watts Link. My whirring started as soon as I installed my noisy-ass Toyo R888s. The noise they generate comes up through my watts link, but it is acceptable to me for the improved traction.



So, do you have noisy tires?

I doubt it as the sound seems like it's coming from the rear. I'd be willing to bet it's got to do with the UCA. Although the tires are the stock goodyears from 14 up front and from 2016 in the rear. The fronts are a little cracked and also mounted backwards to correct a vibration (I know I'm due for tires soon I'm milking them..

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I'm not sure going back to rubber is going to help a whole lot, but let us know how it turns out. While you have the upper control arm off, check how loose the rubber bushing on the differential is. Having replaced mine with poly, this bushing is rather flimsy from the factory. If your car ever had any wheel hop issues, that bushing could be beat to death and cause metal to metal which would transfer even more noise.

 

On gas warring noise, and it gets quiet off gas is a ring and pinion problem. either the tooth alignment is off or the backlash is off. The gears need to be checked and re shimmed again!!!

 

Once upon a time I was an engineer at energy suspension. We fought and fought noise that poly makes. We tried graphite impregnated, fluting, chamfering, the only thing that ever quiets down poly is the grease that we sent in every package. It’s super sticky but over time it wears away.
So we started making some parts with grease zerk fittings, like sway bar brackets and so on.
Poly will squeak like nails across a chalkboard while the suspension is traveling. It will amplify other noises as well. So it sounds like you have a ring and pinion lash problem being amplified by the poly.

If your installer used the yellow marking compound and checked the tooth pattern on the acceleration and coast side of the teeth, you would see the contact patch of the pinion to the ring. It shows your depth also.
I’m willing to bet that you are to tight and deep on the acceleration side and to loose and high on coast.
When you let off the gas to coast, do you feel a slight jog as if it went limp then the car starts to slow?
That can also be felt under slight acceleration from a stop.
Say your loose and high on accel then tight and deep on coast. If your at a stop and then slowly start to go, you will feel the gear engage a split second before you move.

Ford racing 3.73 are notorious for gear whine. I did a lot of research because mine were just ungodly loud. I sent back 2 sets because it was unbearable.
I found out that a casting with a certain number was a bad batch. I think it ended with an “m” or something.
If you put in ford racing 3.73’s then you may have gotten the batch number that was responsible for excessive gear whine.
I switched to Richmond and they are quiet as ever.

 

I have read that you need to run on the tighter side of the backlash specs with the 3.73s. When I installed the Eaton TrueTrac in mine, the backlash was .009" and that's where I reset it. Mine doesn't whine like I've heard some people describe. And while I am do have a hearing impairment for higher frequencies, my wife doesn't, but I can hear her complain and she hasn't.

 

Exactly right, they state between .007 and .011 backlash. I did the same as you, set it at exactly .009, took forever getting it right.
I have a pinion depth tool as well and I set my pinion depth within .001 of what was stamped on the pinion.
I checked the contact pattern and it was exactly centered on both sides of the gear.
No matter how perfect I made it, just super loud whine.
I tried a few different lubes, royal purple, redline and Lucas with none of them making it quieter.
After 2 sets and then switching to Richmond, that made all the difference.
That’s when I found out about the batch numbers. It was to late by then, I had already switched to Richmond and was happy.

The break in is very important as well. If the gears are quiet at first and you do an improper break in, they will seat wrong or get to much heat in them before a correct heat cycle and make noise.
Changing the oil after the break in is just as important.

 

Thanks for the replies guys, I checked out the UCA today and looks like the bushing is destroyed. Unless there is one not visible and is tucked away but due to the dryrotting rubber flaking from one end I am thinking this is and issue. I still cant help to think that they still may need to be re-shimmed. The info on the bad batch of gears is help full too. These are brand new ford performance gears I don't have the box anymore. What do you guys think about these pics of the bushing or lack of. Pics to follow...

 

Also looks like the front of the UCA is making contact with the gas tank.

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The front bushing doesn't look like it's not centered, so it might be cracked and failing. It's hard to say on the one of the differential, but it's fairly flimsy. The bushing is not really solid so it can articulate, but also is a weak design that is not likely to take a lot of abuse, or last a long time. I'm not familiar with that particular arm, but you should be able to get a replacement bushing from the manufacturer. Make sure you use a marine grade synthetic grease. Supposedly mineral base grease doesn't break down poly, but every poly I've seen fail has a mineral based grease pumped into it.