Should be. I believe the 30x numbers are production location numbers.
The replacement motherboard received corresponds to the same exact Intel® Desktop Board DP67BG; the difference is the motherboard’s revision only.
Please feel free to confirm the different AA numbers available on each Intel® Desktop Board at: http://www.intel.com/support/motherboards/desktop/sb/CS-009008.htm
The 304 is a older board than the 306 . If this was a RMA , I would demand that Intel give you a board of the same Rev. # or newer.