The older Marlin's weren't equipped with swivels or a quick method of mounting them.
DO NOT remove the black and white Marlin "Target" emblem from the butt stock. That's not where a swivel is installed.
The butt swivel is installed by drilling a carefully centered and level hole 2 1/2" up from the butt plate.
For the butt, you can use most any type of swivel that uses a wood type screw, including screws that have a swivel attached, or a stud that a quick detachable swivel can snap on to.
For the front, the easiest to mount (assuming you have a rifle, not a carbine) is the Uncle Mike's type swivel that attaches to the magazine tube.
For a sling, a 1" wide sling is better for the marlin than a wider 1 1/4" type.
Slings range from simply leather or nylon carrying straps to the military type leather slings that can be used as a shooting aid.
A good source of slings and swivels is Brownell's:
http://www.brownells.com/.aspx/pid=27299/sku=593-139-100/Product/QD_SWIVELS
There is also a type that's like the front swivel as used on later Marlin's in which a hole is drilled into the steel fore end cap and a machine screw threaded swivel is screwed into the cap.
On this one, you have to be careful not to drill into the magazine tube.
You can also get the Marlin factory type in which instead of a threaded screw, the swivel has a stud that's riveted into the steel cap.
To install this type you have to remove the fore end cap.
That's "touchy" because it's VERY, very easy to cross thread the cap screws.
Because of the difficulty in getting the cap holes lined up with the dovetail inside the cap, you see a lot of Marlin's with cross-threaded fore end cap screws.