cb antenna problem

Your antenna will need to be tall to do that and make it work. I did that with a 102 whip and it worked well. You would need most of the antenna above the cab and away from the cab wall.

In my case, only a foot of the 102 was obscured by the cab and the glass is non reflective. Of course now I have the 108 mounted on the toolbox between both lids and it works excellent.

If you wanted to do that with a Wilson 1000 you'd probably not get out as good as you would want to, both because a good chunk of the antenna would be obscured by the cab (due to only being 5 feet tall) and since most of the antenna would be near metal, there may be a high SWR due to reflect as well.

Here's a few examples of how I mounted my 102/108 in the bed and on the toolbox, both with excellent results:

 

Wilson 1000 is generally for your standered cb up and 10 meter up to about 500 watts and wilson 5000 is for running a lot more power. if your swr on a metal whip antenna is really high on 40 and you cant get it down after lowering it to the bottom of the shaft you can trim off about a quarter of a inch at a time till your swr gets down to a 1.5 or lower

 

you say this is center loaded k40, and firestik works... because the firestik is a mostly top loaded fiberglass whip, everything posted about mount location is correct. I just guessing your load on the k40 is below the roof line? The idea is to get as much antenna above and away from rf ground, with a center load you would only have 2' or so showing. Thats not to say the k40 isn't shorted internally. Try putting the k40 on your friends truck and see if it tunes to be sure.

If were me, I'd change mount location, and / or antenna design.
Good luck!

 

I have run the Wilson 1000 mag mount on my SUV and Chevy truck...dead center of roof and it tuned just fine.
With my Galaxy 44v it talks very well.

 

Certainly try anything you can think of, and each install is different. But I think you miss the point of what's been said here.

 

If your bed is bonded well to the frame, mount it on the bed rail about 2ft back from the rear of the cab, but not right up against the tool box. (This worked well on my 1985 full size Chevy PK, but did not work on my 2000 GMC Sonoma.) Another option that works well is on the front fender, (worked great on the Sonoma) opposite side from the Am/FM antenna. You can use 1/2 of a semi truck mirror mount on the bed rail set up. You will probably have to make a mount to work on the front fender. I used a piece of stainless steel on the front fender set up.