I would start my search at numrich gun parts corp.They can be found on the web.
The value of a Stevens 335 shotgun would actually be dependent upon a number of factors. Some of these factors would be the age and condition of the shotgun.
Try Gun Parts Corp. They have parts for nearly every gun ever made.
The stevens model 335 shotgun was made from 1926-1935,with a total production of 2,000 guns made.
I would check with Numrich Gun Parts Corp.They may have a exploded view of the stevens model 335.
You may find this at Numrich Gun Parts Corp.
The Stevens 335 was manufactured from about 1910-1940. There are very few documented Wells Fargo guns and those that have documentation are not conspicously marked with the company name. These were added by an unscrupulous antique dealer wishing to sell a $200 shotgun for $1000.
STEVENS / SAVAGE HAVE A COLLECTORS SITE GOOGLE IT
Depending on condition, average of $100 to $200 in 2012.
your Stevens arms shotgun was produced between 1926-1935 with only 2,000 total being made.