For those following in my footsteps, ended up being the motor mounts, more specifically the top two.
So a bit of a guide...
Ending up ordering, for a 2011 FF Limited, non-EB.
8G1Z-6038-AEngine Mount
DG1Z-6038-FUpper Trans Mount
9G1Z-6068-ALower Trans Mount
*Note that if you have EcoBoost these will be different, there appear to be 2-3 variations over the Flex lifetime.
From FairwayFordParts.net for just under $200. They checked the VIN for free and were OEM Ford parts on arrival. "Internet brain" consensus doesn't seem to have long term luck with Anchor or the other RockAuto 3rd party brands of mounts, though Anchor does have a kit of 3 (300707) for about $100 if you're willing to risk it.
Install took about 3 hours with 2 people. You'll want a magnet on a stick, various sockets and wrenches 8mm, 10mm, 13mm, 15mm, and a 18mm. Lug nut socket. A variety of extensions. A body plastic tab removal tool. Probably a locking pliers or way to clamp a 3/4ish rubber hose. Flat head screwdriver. General tools. Definitely will need a floor jack and a block of wood. A lift is nice but entirely do-able without, stands would be ok. Get some blue thread locker beforehand for the mount bolts. Potentially a jug of coolant (read entirely below).
I'll link some videos below as to how to go about this.
https://www.youtube.com/watch?v=YlfHFGzrUZg
In my case for whatever reason I had an additional add on to the antifreeze coolant reservoir that made it basically impossible to extract the passenger side top mount thanks to the extra lines. At that point I had the choice of breaking open the AC lines which would have been a big pain, or we had already unplugged the coolant tank's upper hose and it'd leaked out, so myself and a helper basically took off the hose clamps to the coolant tank after unclipping the extra module (has a tab), then quickly wiggled off the hose, spun the tank upside down while plugging the little upper hole with a finger, while the other person held the large bottom hose up long enough to get the engine mount out and replaced it. This is where the vice grips or something to clamp off rubber hose would be needed (we shoved a bolt in the small hose). Not crazy in practice but annoying since the videos imply you can just rotate it and shimmy it out. YMMV. If you're real close but stuck on the tips of the engine side bolts getting the mount out, just drop the jack a little bit. Reassembled the hoses/tank and fortunately I had a jug of coolant on hand to refill it.
https://www.youtube.com/watch?v=2TFd63XVrkE
The driver side top mount was actually pretty easy, mine was clearly blown and leaking oil from the rubber and flopping around. The worst of it was the bottom bolts under the mount. Since we didn't quite have a low profile tool like in the video. We ended up taking off the driver front tire, and you can get in behind the plastic tire well shielding with a long closed-end wrench and just go to town or use a ratcheting wrench. A lot of up and down on the jack to get it centered for the bolt removal and replacement, but otherwise was straightforward and quicker than expected.
The last bottom mount or the "torque strut" as it's sometimes listed as, if you look around here suggests it can't be removed without dismantling the Y section of the exhaust. At least in my case this is incorrect and I have nothing aftermarket or work done to my exhaust. There are no videos on YouTube about this part on a Flex so there's no visuals or references. There's simply two long bolts, the part is immediately visible from underneath. You'll have to use a wrench, ratcheting preferred, and the bolts are long enough to touch the exhaust across from it, but you can shimmy out the bolts at an angle without much effort. Might need to apply some movement to the strut component with a prybar, or I'd recommend doing this first of the 3 mounts, because your motor is probably sagging already and if it was tightened up with the upper mounts being new, you might not have as much leeway to wiggle those bolts out. It took 5 minutes to remove, if that. Easiest by far.
This has ultimately solved the clunking coming away from a stop, no more creaking noises, and greatly improved the vibrations while driving.
So if you're 150K-ish miles on a set of mounts and having suspect noises, take a look at those. Not terribly expensive or hard to do yourself.
So a bit of a guide...
Ending up ordering, for a 2011 FF Limited, non-EB.
8G1Z-6038-AEngine Mount
DG1Z-6038-FUpper Trans Mount
9G1Z-6068-ALower Trans Mount
*Note that if you have EcoBoost these will be different, there appear to be 2-3 variations over the Flex lifetime.
From FairwayFordParts.net for just under $200. They checked the VIN for free and were OEM Ford parts on arrival. "Internet brain" consensus doesn't seem to have long term luck with Anchor or the other RockAuto 3rd party brands of mounts, though Anchor does have a kit of 3 (300707) for about $100 if you're willing to risk it.
Install took about 3 hours with 2 people. You'll want a magnet on a stick, various sockets and wrenches 8mm, 10mm, 13mm, 15mm, and a 18mm. Lug nut socket. A variety of extensions. A body plastic tab removal tool. Probably a locking pliers or way to clamp a 3/4ish rubber hose. Flat head screwdriver. General tools. Definitely will need a floor jack and a block of wood. A lift is nice but entirely do-able without, stands would be ok. Get some blue thread locker beforehand for the mount bolts. Potentially a jug of coolant (read entirely below).
I'll link some videos below as to how to go about this.
https://www.youtube.com/watch?v=YlfHFGzrUZg
In my case for whatever reason I had an additional add on to the antifreeze coolant reservoir that made it basically impossible to extract the passenger side top mount thanks to the extra lines. At that point I had the choice of breaking open the AC lines which would have been a big pain, or we had already unplugged the coolant tank's upper hose and it'd leaked out, so myself and a helper basically took off the hose clamps to the coolant tank after unclipping the extra module (has a tab), then quickly wiggled off the hose, spun the tank upside down while plugging the little upper hole with a finger, while the other person held the large bottom hose up long enough to get the engine mount out and replaced it. This is where the vice grips or something to clamp off rubber hose would be needed (we shoved a bolt in the small hose). Not crazy in practice but annoying since the videos imply you can just rotate it and shimmy it out. YMMV. If you're real close but stuck on the tips of the engine side bolts getting the mount out, just drop the jack a little bit. Reassembled the hoses/tank and fortunately I had a jug of coolant on hand to refill it.
https://www.youtube.com/watch?v=2TFd63XVrkE
The driver side top mount was actually pretty easy, mine was clearly blown and leaking oil from the rubber and flopping around. The worst of it was the bottom bolts under the mount. Since we didn't quite have a low profile tool like in the video. We ended up taking off the driver front tire, and you can get in behind the plastic tire well shielding with a long closed-end wrench and just go to town or use a ratcheting wrench. A lot of up and down on the jack to get it centered for the bolt removal and replacement, but otherwise was straightforward and quicker than expected.
The last bottom mount or the "torque strut" as it's sometimes listed as, if you look around here suggests it can't be removed without dismantling the Y section of the exhaust. At least in my case this is incorrect and I have nothing aftermarket or work done to my exhaust. There are no videos on YouTube about this part on a Flex so there's no visuals or references. There's simply two long bolts, the part is immediately visible from underneath. You'll have to use a wrench, ratcheting preferred, and the bolts are long enough to touch the exhaust across from it, but you can shimmy out the bolts at an angle without much effort. Might need to apply some movement to the strut component with a prybar, or I'd recommend doing this first of the 3 mounts, because your motor is probably sagging already and if it was tightened up with the upper mounts being new, you might not have as much leeway to wiggle those bolts out. It took 5 minutes to remove, if that. Easiest by far.
This has ultimately solved the clunking coming away from a stop, no more creaking noises, and greatly improved the vibrations while driving.
So if you're 150K-ish miles on a set of mounts and having suspect noises, take a look at those. Not terribly expensive or hard to do yourself.