Muncie 420 (I believe

)
Well, I took the plunge and drained my trans. fluid in prep for inspecting my trans. innerds. I ended up breaking the gasket in the process. I planned on replacing it but should have obtained a new one before disassembly. Can I buy these only or will I have to get a whole kit of gaskets?
Well, This came about because I did not like the sound comming from the trans. when I put a strain on it. Even the slightest strain gave me a sort of grinding sound. Maybe 'grinding' is the wrong word here.
I look inside and can't see anything wrong. I seemed to get the proper amount of fluid out when I drained it. I expected to see chunks of metal on the magnet or wear on the gears but I can't see either. Of course I've never seen the inside of a trans. before either.

I can post pics if need be but could someone tell me what I should look for or what to do next? Thanks a million.
BTW, I took some pics before I disturbed the magnet too much so I still have the evidence.
ndn, I may see if you'd have some time in the next several days to come take a look. Would that be convenient for you?
Rance