Tom, if you use the search from the bar above (third from the right after "Log Out", "Quick Links" then "Search"), enter "fuzeblock", you will get 17 threads returned regarding the subject. Here is one of them
The GTL is a bitch to mount the fuzeblock, given it's thickness, on a GTL. I ended up having to wedge it sideways behind the Alpine unit (big grey box). Not the best install, so I moved on to the PDM60 which is waterproof, and no fuses to deal with. It also fits better under the wiring coming out of the front of the Alpine unit.
(image borrowed from iride4u)