About to Attempt full Drivetrain fluid change MKT

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Okay, so my 2010 MKT has just under 90k. I bought it a year ago, not knowing ANYTHING about EB's. I love my baby, but lately she has been dragging her feet, shifting sluggishly, as well as what sounds like a bit of rumbling in the front end of the drivetrain.
I've been on here reading about everything i can, and i noticed the issue with the PTU's... which explains the slow moving and rumbling/knocking. And my Trans fluid is DEFINITELY NOT red anymore, so that can explain some of the slow shifting. I figure i might as well do the RDU while i'm under there... i am assuming the worst... and that none were ever done (i figure it's best to assume the worst and be pleasantly surprised if it's not, lol)
I am hoping that the PTU isnt done... i would assume i couldn't drive it if it were.
I am using Royal Purple 75w-140 for the PTU.
Not sure if i should run Royal Purple 75w-90 for RDU or stick with some other 80w-90.
Since my tranny fluid is so brown, i figure i'll find the first LV fluid i come across at Advance, BUT i would like to know which ones you guys think is best.
I am going with RP for the most childish of reasons... it's purple, and I LIKE PURPLE! lol RP doesnt make LV fluid, or else i'd be going with that, lol

I figure i'll put it up on stands and do all 3 at the same time.

Input?



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[SHOdded]

Purple Rain ... The Color Purple ...  A love well justified   Yeah, RP does not make LV spec'd fluid, apparently   You will be happy to know that a stalwart of the SHO community, bpd1151, uses Royal Purple for just about every other fluid in the engine & drivetrain, so you will be in good company.  He sticks with Motorcraft Mercon LV exclusively for the trans, so I would recommend getting a caseful at the dealer, hopefully get a good price on it ($5-6/qt at case price).

Exactly HOW brown is the trans fluid?  Does it smell burnt?  Does it have debris (visible or on a blot test)?  Mercon LV changes color over time, from red to brownish, and apparently it is a natural progression:
! No longer available
Ford Transmission Tips: #2 Mercon LV Fluid Color- What You Need To Know

A 2x or 3x drain and fill process on the trans should be good enough, no need to flush, as the condition of the trans is unknown and you don't have access to look at the internal screen (no replaceable filter).

The PTU is a tricky little bugger, and can get you in oh so many ways.  I do hope that the fluid is at worst thick & black, with no contamination from trans fluid (seal leak) or spewing from the vent.  Lincolns seem less prone to these issues, but somebody has to be the exception LOL.  Be prepared for a fight during extraction, and 2-3 rounds of R&R of PTU fluid before you call it a day.  RDU is more likely to be OK.

Rumbling though is usually more of a wheel bearing issue, so I would check to see if the wheels rotate freely and noiselessly.  Does the amount or volume of rumbling change depending on which side you turn the steering wheel to?  Rear wheel bearings might mean the control arms have to be replaced as well to prevent return of the issue.