Got the new manifold and muffler on and beside dropping and losing a nut and having to go to town for a replacement it all went on just fine.  Today Fenn and I were going to change the oil in the differential.  The first challenge was figuring out how to open the fill plug.  It's located at your feet when driving and has a big square recess so you need something big and square to open it.  Here's what it looks like:

The recessed area is about 3/4 inches and I didn't have anything that size so I went to the hardware store and bought a plug that had the male version of this and with a little grinding it fit and by grabbing that with a pair of channel locks I was able to spin it open.  Here's the plug:

So far so good.  To drain the six gallons of oil from the differential there are two plugs; one below the PTO and the other by where the belly pump is supposed to be (it's missing from this tractor). Expecting there would be a fair amount of old crud in there I first poured in about a half gallon of kerosene and drove around for a bit to loosen things up.  Fenn pulled the first plug near the belly pump and the oil that came out didn't look to horrible, a bit of water but that was about it.  When he pulled the rear plug a lot of water came gushing out then some oil.  I'm guessing there was maybe four gallons total we drained.  When the rear area was finished draining I looked in the hole and saw something so I stuck my finger in and pulled out a bunch of metal pieces (crap!).  This can't be good.  The pieces look like they were part of a bearing.  I'll post the pics on the Yesterdays Tractor Magazine website and see what I can learn before replacing the oil.  I was hoping to not have to get into the transmission but that may now be in the cards;

The new manifold and muffler installed .... much quieter