K5LA install in 08 F250

Well, I finished my install of my K5LA in the truck box of my 08 F250. I have always had a problem with planning projects like this, so it seems like I am constantly running to Home Depot or running to Walmart for that “one last thing” that I forgot to buy. The fact that a lot of this stuff (like air fittings) can’t be bought locally, made it a long process of getting everything I needed. One last trip to Walmart last night at 2:00 AM to buy an 8 gauge amp wiring kit did the trick. I know my wiring is a mess in the pictures, but I have that all fixed now. It’s loud…200 psi of wonderful noise!

I will post up a video some time this week. I have to go far away from the house to make a video though. My wife hates the horn…probably because of the $1000+ that I spent on something so stupid!

Nice. I never thought of doing it that way.

my wife said the same thing and now that im selling my truck and i’ve gottin a car. I tld her i dont know i i want them anymore and she flipped out on me and told me that i better not sell them.


rich… its possible i might slap you if you dont put those in the vic

what all is the OTR restrictor and what was used to remove it

Hmm, well I suggest 2 things… first, would be use at least a 1/2" selenoid, k5’s are already stuggling for air pressure using a 1/2" so upgrading would get you louder…and the other thing, mount the horns under the truck. Creative thinking, but would be oh so much practical loud underneath the truck because the sound won’t be encased in the bed…

Other then that, great install!:slight_smile:

ps: All the fittings I’ve used came from lowes/homedepot :slight_smile: No need for fancy connectors :cool:

It’s a small restrictor that is installed inside the manifold. here is a link to the picture of what it looks like. All you have to do to remove it is stick an allen wrench up inside the opening in the manifold and unscrew it.

As you can see, the hole in the center is much smaller than the outside diameter of the restrictor. This is what makes the “Over The Road” K5LA legal to use on the road.

Many people do not realize that the only difference between the standard K5LA and the “Over The Road” K5LA is that small restrictor. I wish the people on this site would post that information up and sticky it so that people wouldn’t get ripped off by sellers on eBay claiming that they are selling “real” K5LA’s that are so much better than the OTR K5LA.

oh so its just a smaller port not letting in as much air…remove it and you got a normal nathan horn…makes sense…good post!

Aren’t the “real” ones on ebay cheaper then the OTR ones though? As far as I can see, the OTR’s are $1300-$1600 and a regular K5la is about $1100

That’s only because the OTR horns are direct from Windham Machine. The “real” ones are cheaper because they are usually used/restored and off of a train. It’s kinda like you can go to a junkyard and get a part for your car or you can go to the dealer, which is gonna cost more?

damnn such a nice truck

now that is a sweet idea and install! great job!

Thanks guys. I am working on getting a video clip. I work nights, so sometimes it’s difficult to get things done during the day.

Nice truck and install. I like the horn inside the toolbox a lot. I’m wanting to do a setup similiar to this eventually, but leave my nathan under the truck and put the shockers like you got your k5, except cut out the bed and point the shockers down to the ground.

thats a sweet truck