Plug the phrase "Marlin Model 99M1" into Google, and you'll find a wealth of data and sites relating to this firearm.
In today's market in 90% condition you should expect to get around $95 to $115 Jan 2013
Remove the trigger assembly. It should only be 3 screws. The serial number is located on the bottom of that plate. (At least it is on my model 99 m1)
try looking under the trigger guard. That's where I found my Model 99 M1 Cal-22LRserial number
Marlin has manufactured machineguns and submachineguns for the US military, as well as making M1Garand barrels, and parts for M1 Carbines.
100 USD
The 99m1 was built from 1964-78. It was built to resemble the original M1 Carbine, as used in WWII. The 99M1 is the same gun as the Marlin 989 or 99C, so parts interchange with them. Answer The 989M2 is the clip-style magazine, as opposed to the tube style found on the M1 :)
try Numrich Gun Parts Corp.If they do not have one,maybe Marlin itself may have a few still in stock.E-bay would be another good place to find a stock for your rifle.
This rifle was made by Marlin during 1960-1965 it's value depending on condition is $40-$70. see http://books.google.com/books?id=dtXAksiLURkC&pg=RA3-PA1044&lpg=RA3-PA1044&dq=marlin+model+80g&source=web&ots=wu_O36jw_D&sig=reNmkhSBnkgNNrxCF915RJndXaw&hl=en#PRA3-PA1044,M1
You can not, there are no conversion kits from an m14 model to an M1
US military for model #1.
45