The Standard Catalog of Smith & Wesson list the bodyguard serials as:
1982 = J915401 - 1J18600
1983 = 1J18601 - xxxx
1984 = starts at ADT3000. So the only place your serial # 9J6xxx will fit is 1983.
I guess I should have just told you 1983 from the start instead of confusing it with additional info. Hope this helps.