A Sears Mod 53 is a Winchester Mod 70. If Sears doesn't have an owner's manual for the 53 (and you can't find one on eBay), go here http://www.stevespages.com/page7b.htm for a Winchester manual.
Go to remington.com and print one off.
100-400 USD
No published sn data.
The model number is 117
1958 model 70 Winchester 3006 good condition
250.00
You can get an owner's manual from Remington. Check their web site.
Impossible to answer without a DETAILED description of ALL markings.
depends on what model it is as well as the age. need more details on the rifle.
3006 weeks = 3006 x 7 days = 21,042 days
You can try Numrich gun parts, ( e-gunparts.com )
200 to a few thousand depending on EXATCLY what model it is.