I have 3 NMO's in my roof. Its an easy install. You gotta drop the headliner and pop the holes where you want. I used Antenex's NMO saw. It has a set depth so you dont go ripping your insides apart and it works very nicely. Than i ran the coax with the bottom half of the mounts from the inside, put the retaining ring on from the outside and screwed on my antennas. Than just reattatched the headliner and ive had no problems since. All my antennas are antenex's-a phantom UHF, cellular look-a-like VHF, and all band scanner in that order from front to back. Heres some pics of the install.
The Antennas:
And my radios:
The one over my rearview is a Motorola CDM1550 VHF and the other is a Motorola CDM1250 UHF. Both are remote mounted with the main part of the radios under the drivers seat. The VHF i use for my fire department and the UHF for GMRS and scanning mostly.
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