Vishal,
SDK 5.03.03 is very old and no longer supported.
SDK version 06.00.00.00 is the last SDK based on kernel 3.2 and SDK version 07.00.00.00 is the latest SDK, but it is based on kernel 3.12 and it uses device trees. Because of the big differences between these two versions of the Linux kernel, SDK 06.00.00.00 will continue to be supported in the near future alongside with SDK version 07.00.00.00.
You can check this wiki page which covers how to build the new linux kernel and the needed device tree files: http://processors.wiki.ti.com/index.php/Linux_Kernel_Users_Guide
Information about the device tree concept can be found on the web.
There are also the following wiki pages about the AMSDK U-Boot:
http://processors.wiki.ti.com/index.php/AM335x_U-Boot_User%27s_Guide
http://processors.wiki.ti.com/index.php/AMSDK_u-boot_User%27s_Guide
Best regards,
Miroslav