No published sn data
The best that I can do is state that the Stevens model 311 side by side was discontinued in the year 1989.
1912
model should be on top of barrel or side.......................
The year should be stamped into the outer side of the tunnel.
Need to know the year, make and model.
Need to know make, model and year to answer that and remember the right side is the passenger side of the vehicle.
The year, make and model info would help.
My car is 2006 model Buy Wix PN 24477 (~$13 rockauto or amazon) Open rear hatch door. On drivers side there is a plastic cover near back on side. Snap open and off. Press 2 tabs to release filter door. Slide white filter out of holder. Watch air flow arrows (down) and side in new filter. Replace filter cover. Snap trim piece back in place. Wait 10,000 miles or 1 year and do it again.
It would help to know what the year, make, and model of vehicle is, as there are different mirror assemblies in use.
On the upper right hand side of the transom, the model / serial number plate is affixed. The last two digits in this number is the year model.
Re-submit question including make, model and year of vehicle.
Depending on the model and year...replace the relay.