1991 Explorer Trans

I removed my transmission this week-end. It went pretty smooth except:

1) It was a pain getting at the top bolts of the bell housing.
2) It was a pain removing the metal part of the dip stick from the
trans. After I pulled the tube out I had to use a screwdriver to put
pressure on the side of it so it could be wiggled out.
3) I didn't have a 16mm flair nut wrench and then when I got one it was
hard getting it on. After I removed the transmission I found I could
remove the heat shield. That may give me better access.
4) It was a pain getting the transmision over the exhaust pipe. After I
got it over the exhaust it seemed to come on out.
5) There was a metal hose coming from the engine compartment connected
to the trans via a rubber hose. My book didn't tell me to remove it and
I saw it while tugging on the trans.

I was looking for my trans number. There was a number like:

P90GT 7A049 BAR imprinted on the right rear. Is that the Part Number?

I'm looking for another or someone to rebuild this one.

I was talking to a rebuilder and he was telling me to cooler needed to
be blown out before this is put back in. Anyone know anything about
this?

Also I noticed that the O2 Sensor in the exhaust is in a place that I
doubt would be removeable if the trans was in the car. Should I go
ahead and replace this?

Mike