if it's a Freightliner Cascadia and you draw a line at a 45 degree angle Forward and up from the mirror bracket on the door it will intersect with bottom of the windshield and at that precise point you will have the least amount of interference from body panels interfering with your antenna on a Freightliner Cascadia. I don't know of anybody that's been able to get it totally vertical and have it tune correctly on that particular truck
Thanks for the info. I'll try angling the XM antenna to see if it helps with the reception in certain directions. When going W to NW the reception sucks.
I'm pretty sure if you duct tape a few $100 bills to your radio it will outperform most stock radios. If that doesn't work look for a CB shop and give them the $100 bills and your radio should be able to talk to the Intl Space Station.
Ok ONE more time ALL i run are wheeler dealers yep long almost 4 feet only had one break. robin did it using a 6 inch pine limb! but some of you guys know but here it is NEVER use the factory installed coax 40 seven million reasons. Keep them vertical. if your mirror brackets are plastic run a ground wire to some kind of metal. I could write a sticky if any one's interested 30 years of stuff kitty power