I did a Google search for J. Stevens Arms and found they had been bought years ago by Savage Arms. I called Savage today and they gave me a number in Florida of a company that does that "old gun" repair etc. I called the Florida store. They were helpful and seemed knowledgeable.
Here is their info:
The Small Arms Shop 352-637-4770 Savageparts.com http://www.savageparts.com
The website has other info of course.
where can i find replacement parts for a 22 caliber Stevens modle987
One can find parts for a Stevens model 35m gun at local gun shops. Gun suppliers also carry parts of many types of guns.
I seem parts for your gun on e-bay
We have parts for that model. email@example.com
Parts for a Stevens Model 87A can be found at: http://www.e-gunparts.com/productschem.asp?chrMasterModel=089Zz87A
Riverside was manufactured by Stevens, so if you can identify the equivalent Stevens model, you should be able to find parts. Check with a local gunsmith.
Try Numrich (gunpartscorp.com)
Go to Numrich Gun Parts Corp.
NUMRICH HAS PARTS FOR THE STEVENS 66B
try gunbroker.com they might have parts