It should be embossed on the hull on the starboard side of the transom just under the vert fittings. Unfortunately if the hull has been painted or repaired in that area the number may be gone or unreadable.
I'm not savvy on how to read the number. There are a few threads in the archives where the sequence is explained. The most important parts of the number is probably the year built and the number which it was built that year.
The number before the M is your hull number. 82 is the year built, and the A designates the month, but you need the guide to tell which month A stands for. My Morgan 383 hull number ended 040M82L, and was hull 40 of the 383 model