Thanks for the responses. I apologize for not doing my homework before posting.
The first thing I discovered (by my belated research, and inferred from Terry's response) is that the right and left seats are somehow different. And the second is that the seats used in my G model have the same part number as several earlier models but different from ones starting just one or two models later. So what I really need is a seat (preferably left side) from something with S/N 15060773 - 15067198. Left seat is P/N 0400118-65 and right seat is -66.
Thanks for the suggestion, Eric. Although I've kept my plane at the same field for about 15 years, I know only a few other pilots there, none of which fly a 150, and the rentals are later models. But I have seen a couple of other 150s there, so I'll ask around.
Roy