Just fair warning. O'briens, in my experience, is somewhat hit or miss. I've ordered from them twice and both times, eventually, I got what I ordered. However, this was not without much hassle and delay. If you need it quick, I would call them and place the order on the phone and hold their hand through the whole process. Even then, you might have to stay on top of them to get the order shipped.
To be fair, I didn't get screwed and they did make good, but the time it took was simply ridiculous (we're talking WEEKS here). Short version, if you want or need your servos NOW, you might be better off shopping elsewhere. If you are patient and don't mind babysitting your order, O'Briens will probably get the job done.
Just my thoughts....
Erik