Thanks Garth! That's a good resource as long as folks have some idea when their gun was made already. I've seen some people enter serial numbers for guns in the 1906-1941 range, and get replies that indicate their gun was made in the 1870's or 1880's. It also doesn't allow for the prefixes used in the pre WWI era Marlins.
If you enter the early number such as C19xx, it will say it's invalid. If you drop the prefix letter, it will tell you the gun was made in 1884. Had a guy offer me a model 1893 with the above serial number, which he checked at that site, and he swore it was made in 1884! Had a devil of a time convincing him they didn't make them 9 years earlier!
Yes, if one goes to that particular website, they must first realize that Marlins made after 1906, and especially those with LETTER PREFIX serial numbers before the Model 1936 came out are going to be difficult, if not impossible to age at this time. There are, however, members of the old "Marlin Talk" board who are gathering serial number records and gun descriptions in an attempt to try to reassemble where guns should fall in that 30 year period. Hopefully, these good folks will eventually show up here on MarlinOwners.