http://www.rrarms.com/catalog.php?prod=M74NThis is what i use in my Arsenal SLR, but you will need minor fitting to make it work with a SAR-3. Real SAR-3 mags (Weiger mags) are hard to find and always super expensive.
Promag makes a mag too, but when i did my research before buying 10 mags, i decided the Bulgarian "Circle 10" mags were the way to go, as they seemed to be more reliable, stronger, and only a little more espensive.
This was one of the reasons i decided to get the Bulgarian .223 AK instead of an older Chinese or Romanian. There's plenty of factory mags for the Bulgarians but mags are hard to find for the Chinese and Romanians.