A model 49 could vary from 40-150. Never heard of a model 48. Might be a misstamp.
You can tell how old your Ithaca gun is by the model and serial number
Its an Ithaca Flues model made in 1921
If that is an old double barrel "New Ithaca Double" it was made in 1926.
Its an Ithaca Flues model made in 1921
You have an Ithaca Miner model made in 1907
Late 60s to early 70s
the age of a 12 gauge Ithaca is : 47,000 years old .
If this is an old side by side it would be a Baker model made in 1886. Serial numbers of Ithaca shotguns for that year were 2448 - 4101.
Late 60s to early 70s
Made in 1949
1949 production of Ithaca 37's began with serial 202951 and ended with 302500.
Your serial number indicates that you have a Ithaca crass model double,that was made in 1903.