I'm happy to help and very glad they're sending you a photocopy of the death record. Is the gravestone just for him or are there are people on it? Sometimes if a person dies at a young age, but the stone isn't erected until years later (as in, when his wife dies),the birthdate could be supplied by someone who's memory is failing. Was he born in Poland? If he was and you find out when he immigrated to this country, the immigration record may help you. There is also the the birth month and year on the 1900 US Census,if he was here then. The death certificate and obituary info were supplied by someone at the time of death,and if you can't discover any other information as to the correct date, I would give more weight to the calculated birth date. Again, Good Luck. These things can be very frustrating.