I do have a friend that bought a new 038M, I think it was in 1989, but I may be off. It was the year that the 044 was a new Stihl introduction. He still has the advertisement from Stihl about the 2 saws. He was looking for a stumping saw and the dealer led him to the 038 over the newer lighter 044. The saw hasn’t had any work or even a carb adjustment screw turned in 34 years and still runs, even with moderate commercial use and 50:1 red armor.
His saw is a very late one and is Brazil made. The top badge only says “038”. There is no magnum designation on it. At the end of its run, I believe all 038’s sold in the USA were 52mm mags.
The Mag II were typically german made from my recollection. If you have a 52MM saw it’s probably all original, but someone coulda swapped out you muffler.
Do the chop stick/drinking saw measure through the ex port and see what size cylinder bore you have. In addition, if you post your SN, there is a way to find out the year it was made.