Your Marlin model 336CS(Carbine Sporter)was made in the year 1987.
Your serial number indicates the year 1987.
Have it examined by a good gunsmith first.
1995.
1976
1978
150$ to 250$ is my best guess
You will need to add the serial number,to get the answer to your question.
Your serial number indicates that your model 782 rifle was made in the year 1981.
Your serial number indicates that your Marlin model 782 was made in the year 1977.
Double check that model number, I believe it actually reads 336CS. The Marlin 336 in most of its variants is valued as a shooter, in the $150-$225 range. sales@countrygunsmith.net
Made in 1963
Your Marlin model 783 was made in the year 1971.