The CROSMAN 760 Powermaster started production in 1966 then went through 8 different changes and ended in 1991
You need to state what condition it's in. without more information it is not possible to answer you.
You have two choices. First: Crosman has the parts manuals online along with the owners manuals. (See the links below) there are several versions of the 760 so look at each one to find yours. Then contact Crosman for the parts you need if they are available. (Customer contact.) Second: If you have no luck with that, Crosman offers a free service to locate shops that repair old Crosman products. So see the 3 links below.
There are several versions of this model. Here is the web page for all of Crosman air guns. Owners Manuals and Schematics. See the link below.
It all depends on the current condition of the rifle. You have not given description so it is not possible to give an estimate of value
The Remington Airmaster is rated at 725 FPS (Feet Per Second). The Crosman 760 Powermaster is rated at 595 FPS and the 760P is rated at 600 FPS. 10 pumps each.
It's usually just in front of the trigger guard. It should be a 9 digit number.
There are several variations of this rifle model 760. I suggest you contact Crosman corp. They still have some parts available Go to www.crosman.com and contact "customer service."
It appeared around 1966 Source "Blue book of airguns."
This air rifle was made for Montgomery Wards under the Revelation brand name by Crosman. It truth it is a Crosman model 760 First variation. 1966-1970 Average price in good condition is $15.
The Crosman 760 doesn't shoot Bullets it shoots BB's or .177 caliber Pellets.
There are several versions of the 760. See the link below for all of the crosman models with dates and manuals.