Yes they come in 12 gauge iv'e got one.
Marlin
The original marlin model 55 shotgun was made from 1950-1965.This was before the gun control act of 1968 which mandated that all firearms have a serial number.
Model 49, 3000 made form 1925 to 1928 only
From what I have seen and heard Marlin serial#'s are easy to read just take the first numbers in the serial # and subtract them from a 100 and that gives you the year it was manufactured. example: yours is 19 so 100-19=81 so 1981
$100-150, depending on condition.
From ad on web the spiegel 31c was same as marlin model 55, may help in finding the 2 shell clip.
50-150 USD or so Ranger 103-1 was made by Marlin and is the same gun as the Marlin Model 90. If you can get one for $150, I say buy it!. If the the gun is a shooter and in reasonable shape, should be worth at least $250.
This is actually a Marlin 120 with a cheaper grade stock. In good condition I would take less than $200.00 for a sturdy and reliable weapon. It has been mechanically compared to the Winchester Model 12.
Hopkins and Allen arms co. 12ga serial #5832006
It's a Stevens 620.
Mossberg
What do you want to know? I have an 1889 12ga. pump marlin, I would like to know how to remove the foregrip,to clean and possibly work over. Also if you might have some litriture about this shotgun you could e-mail to me,or if you had a ph. no. I could call and talk with you about this. thanks in advance Joe