CNY_Dave

It can be tough to find snow tires with a really proper speed rating for the car- what that translates into is a whole lotta ugly during an accident avoidance maneuver. Can be compensated for if you are expecting it, but it makes a tough maneuver tougher. I had graspic DS2's on my porky gen2 LL bean (like a Q speed rating, really low), had to make a quick maneuver once- tail shook the dog about 2-3 times before I calmed things down.

Exhaust hitting at certain engine torque positions? Bad trans mount? Bad or misadjusted top-center trans mount? (the little dogbone)

Those little things can eat the whole day! Now if you had to do 4 things or so to get to the point where you could actually file the burrs- that's 'yak shaving'!

If the ringing sound was like a musical 'ping' when shifting D->R or R->D that's a classic universal joint symptom (front-rear driveshaft)

Probably no swap needed. Not sure about yopur gen, in gen2 the outback and legacy front diff had different ratios- you might need to swap the rear diff too (or, when you aid trans and diff it may have been rear diff you meant already)

I have done a few tanks now, pretty consistently 21.8, rural, lotsa hills, mostly gentle driving.

Drain and fill typically about 4 qts. make sure the pan isn't dented, even slightly can cause issues.

It threads in on the front somewhere, typically the hole is under a cover, so a chain can be attached for tugging or strapping down.

I regard 'flush' as a scary word...

Just thinking maybe synthetic diff lube might have a little less loss.

I'd chase the misfires before chasing the P0420. Misfires cause extra O2 in the exhaust, which can trigger an 0420. The 0420 is almost never a bad cat.

My '03 H6 had a long-standing complete non-issue external weep that the subaru coolant goo controlled for right up to about 270,000 miles. Mine developed an exhaust-to-coolant leak shortly before 270,000 miles, no symptoms if you didn't drive it hard, but needed too much other work to try to live with it or to swap in a boneyard engine.

Synthetic diff lube front and rear? Maybe a wing to help guide air to fill the 'bubble' behind the hatch?

Ratchet wrenches usually have a lot of 'lead in' that leaves a bunch of bolt head unengaged. I like to take a spare/cheap 6 pt socket and grind off the lead-in when things get sketchy. Or on an important job, one of the good sockets.

I just bought one of theirs Sunday, yeah, nice new bracket. Returned it when I found the '03 OBW caliper I had would fit my '05 Forester.

Sounds like maybe 'miles to empty'.

Heat, kroil or PB Blaster or wax when hot or 50% atf/acetone and one of those bolt-grip sockets from irwin. The wax trick is very old school and has a good reputation, have never tried it myself. Trick is to get the correct part a little hotter than the other. If you can get the rotor off (breaking it?) you can apply whatever stuff to both sides of the bolt.

I refuse to touch exhaust work or suspension work without the blue wrench... An acetylene oxy setup is not that expensive and handy to have.

Is 3rd and R only what limp mode is like? That is, what the trans does when it loses all electrical power?

Could it be in limp mode- loss of power or ground to the trans?

Tow with engine running in neutral?

For the secondary air pump, perhaps?

Any pranksters in the house?

Wow! Chunks in the front diff lube?

The LED flashing probably drains the battery less than the battery's own internal resistance- no real affect on charge life.