can anyone tell me if the 2 o-rings, which are near the end of
the stem which goes thru the center of the oil filter, are both
the same size? Also, are they the normal shape of regular
o-rings or are they sort of flat ? Thanks, I would like to know
before I change the oil.

Did you mean to refer to a 1983 300 SD perhaps? If so, the two o-rings on the end of the stem are indeed the same size. They are also round. Well, at least they are round when they are new. The heat of the oil and engine take their toll on them and they start to look more like a rubber faucet washer than an o-ring. Many people keep a number of these o-rings handy and change them fairly frequently.

thanks MB_Soot My question is totally answered.