TwistedT's review made me think of something. On the Explorer, which I realize is not a Garrett product, the band (biga$$ O-ring) that is supplied to mount the transmitter isn't big enough for mounting it on the Explorer, unless you get a longer jack cable, then you can reach the upper shaft, but it's only long enough to reach the below arm battery housing area. I ended up just using a big ribber band, and it works fine, and they're easier to replace, and a lot cheaper when the time comes.
So depending on your machine, you may need to improvise how to mount it. Someone else uses velcro on their e-trac.