Ruger's web site has sn data. 75-160 USD or so
Do a search on the "Ruger Old Army User Manual". It is a free download and will answer all your questions.
The butt.
To the best of my knowledge Ruger never made it's old army revolver in .36 cal, only .44 and .45 caliber. Many other manufacturers made a similar looking Remington copy in .36, it could be one of those.
No serial number data published.
about 1976
It was made in 1924.
there are far to many #s to be a proper serial #
I bought a Ruger "Old Army" black powder revolver in 1974, which is based on the Black Hawk frame and it came in a RED box with the White Ruger logo. Most Rugers came in a box like that.
You can download the manual for the Old Army cap & ball revolver that has loading and cleaning instructions from the Ruger website (see related links) under the customer service heading.
On the underside of the frame
Around 1885.
Proofhouse.com has Colt sn info