There is a plate rivited to the side of the trans. It will have a series of letters on it. These will id your trans and what it came in.
http://www.442.com/oldsfaq/oftrn.htm#TRAN Auto Transmission Identification
TH-200-4R
The tail shaft is not removable - it is part of the trans housing casting.
Pan Shape
The TH-200-4R has an unusually shaped pan that almost looks like 2 parts. But the pan looks very different than the TH-350. It has a main pan and what looks like a small secondary pan at the rear. All TH-2004Rs have the word "M E T R I C" stamped on the bottom.
TH-200-R4 ID's:
ID Year(s) Application
KZF ** Olds 442/Hurst
CZF ** Monte SS
BRF ** GN/T-Type/Turbo Regals
OZ ** Hurst Olds
OM Olds 350 Diesels
OG Olds 307
BY V-6 252 Cars
AA and AP Cadillac's
Transmissions marked "**" have a special (better for performance) valve body, plate, 1-2 servo, 3-4 servo, 2-3 intermediate servo, and governor.
These codes can be found on the passenger side of the transmission near the output shaft. Sometimes they are hard to read due to the catalytic convertor getting in the way.
The valve body itself will have the first two letters painted on it. Be careful because the paint comes off easily. The special valve bodies usually have a purple strip on them
I personally like 2004Rs better. I pounded on one for many miles with a Pontiac 455 and it's still hanging in there.