Try e-gunparts.com
Rossi
You will have to contact Rossi or find one of their catalogs
100-450 USD
E-gunparts
Check at Numrich Gun Parts. They have a online catalog with breakdown diagrams.
Try Numrich.com
The tube that slide in to keep the bullets in
The Sears Model 42DL .22 caliber rifle was manufactured by Marlin Firearms, their Model 80. Check with Marlin for parts availability.
Follow the link below to the parts diagram from the Numrich Arms website.
you can find parts for your Stevens at bob`s gun parts .com
Try e-gunparts.com
Rossi IS the maker. Rossi is currently owned by Taurus.