Hi there,
49933 is the highest 'standard' build TS2010 will go to.
49938 is the Multiplayer Beta build. To use this, and sacrifice Compatibility Mode, you must install a second copy of TS2010 and patch it to 44088, then 46170, then 49938.
Some TS12 content can be backdated. For most assets this is simply done by changing the build-number to 3.3 but some assets require a bit more work, such as ones with TS2-only tags in the config file.
Kieran.