If they are anything like the square EMITs, and judging by the P/N's that loquatious posted they are, then the different model numbers of EMIT-r's were probably designed with different strength magnets in order to taylor the tweeter's output for each speaker model. So, you CAN try an EMIT-r from a different speaker (and you won't harm anything), but there's a chance that the output may not be optimized for your speaker.
However, all is not lost. It appears that all EMIT-r's use the same diaphragm. While I have not looked at one myself, it is most likely possible to harvest a good diaphragm from a working tweeter and install it in your EMIT-r frame. In this way, you have the magnet structure from your speaker so you'll be sure that the output matches up.
If you try this, take your time (the diaphragms are fragile), and make a jig to keep the tweeter halves lined up with disassembling/assembling. These tweeters have very strong magnets inside and if they aren't held in alignment, they can slam together and pinch your fingers or (worse) damage a diaphragm or break magnets.