I am not sure about the diagram,but I would check at numrich gun parts corp. first for the parts you need.
Contact Customer Service for Savage Firearms. They have owned the Stevens name since the 1920's.
www.gunstockinc.com
Buy parts for 410 Stevens model 67 pump shot gun.
I have parts for that model. sales@countrygunsmith.net
Check on Numrich gun parts corp website.
Yellow pages category = GUNSMITHS.
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.
I would check with Numrich Gun Parts Corp.They may have a exploded view of the stevens model 335.
Numrich Arms should have them.
A FEW parts are available from gunpartscorp website.
Numrich gun parts. Parts availability depends on if you have an old model or new model. There is a nice schematic on their website listed under Stevens 101-7
I would try Numrich gun parts corp.They may be found on the web.