When I'm cruising down the road, I hear a whining/whirling/howling noise as soon as my foot touches the pedal and stops as soon as I'm off of it. After doing some searching on here it seems like it could be the front pump or planetary gears in my 727. Is there any way to distinguish the two without pulling the trans first? If it were the pump, would it not whine in Park since the pump doesn't operate then? What else 'could' it be? I thought maybe it was a torque converter bolt hitting the inspection plate but it makes the same noise with the plate removed. Converter is new also.

The trans was used but had been beefed up for drag racing. I understand sometimes aftermarket parts can be noisy, could that be it? The trans shifts fine and otherwise doesnt have any problems. It has a deep trans pan and is full according to the stock dipstick.

rear gear, ring and pinion. The trans pump works in neutral

Are you sure its not coming from your rear end? Thats the way they'll typically act when the Ring & pinion either isnt quite set up right, or is just worn. Once you plant the pinion into the ring gear (foot on pedal) it makes noise, once you let the pinion float a little (foot off pedal) noise goes away.

This condition would be much more typical than a tranny making a whining noise.

Well the rear diff had crossed my mind but the unit I'm running I bought off a member on here that only had 500 miles since a rebuild (by dr diff actually I believe). I then had the 3.55 gears swapped out for 3.91s (used) and had a new pinion bearing installed. The guy that did the install said everything looked fine inside.

To eliminate the rear end, I should be able to put the trans in neutral and if I still hear the whine when I give it some gas, that would indicate its probably transmission related correct? If it doesn't whine then its probably a rear end problem correct?

It sounds like the ring and pinion was not set correctly when swapped out. Now that you have the whine you will probably always have it unless you replace the ring and pinion and have it set properly.

the planet gears do whine a little IMO when in gear at slow speed

at least all mine have had what i think is the tranz planet gears whining

rear chunks can tranzmit noise up the shaft

but..rear axle most of the time drowns it out when bad from my experiance

dont think you will hear it in N or with the drive shaft out if its the tranz gears

swaping to the "used" 3.91 is not the docs work IMHO

just cause the gears and diff looked good is another thing

"used" is key word here when it comes to the rear axle makeing noise

Yeah I know I took a chance on the used parts but I like to roll the dice once in awhile, sometimes I get burned sometimes I get lucky.

Anyways,

I just jacked the rear up, started the car and put it in neutral...couldn't hear anything. Put the car in gear and again, couldn't hear anything. Now I'm all sorts of confused as the noise is very apparent when driving but I'm not hearing anything now.

Kinda makes me think it could be the rear end now since theres not really a load on it. If it were the front wheel bearings wouldn't they whine all the time until I turned?

You are correct, it's not whining because there is no load. It could be that the gears were used OR they were not set up properly. You can make a new set whine if not set up correctly.

typically it is the r&p, ir the pinion bearings, eitjer whines when on gas and not when off gas, or vice veresa, typically in a factory setup, and worn out vehicle it whines when you let off of the gas, the coast side of the gear.

I had an ex-wife that would whine, once in awhile on hard acceleration.

What Mopar Country said, they need to come out. A reset MIGHT take away SOME of the noise but the odds are not good

What type of fluid are you running in the rear? I'm becoming convinced that syn allows the gear in my DD to transmit a noise that wasn't there with the standard goop.

Whining on acceleration is often heard from the passenger seat area. Or is that screaming

I used to have a Buick GN. Most of the time she would say it just tickled her tummy. Once in awhile I'd get stupid, and hear the whine.

Your whine is coming from the coast side of the R&P.
Once a R&P starts to whine, there is usually no way to stop it, no matter how it is set up, even lapping the teeth is of little use.
Best cure, new R&P.

Any time you take a set of gears out of a carrier, then re-set it up in a new carrier (i.e. USED), its gonna make noise. There is just no way to get them absolutely exactly the same as they were in the other carrier. The good news is, it doesn't neccisarily mean anything is wrong. Plenty of gearsets have lived for years and tens of thousands of miles, singing all the way along.