Thanks Train Man.
I found a local Kenworth dealer and spoke the the parts dept.
They told me they dont carry the Grovers but can order them.
I only asked about the 1054 & 1055, which they quoted me $175 ea, out of Las Vegas.
I'll call them back about the 1056, which may be a little cheaper since it's a combo of the two.
Air horns of Texas has the 1054 & 1055 for $115 ea, and being that this is going on a car, may be my best option (due to lack of room).
Question:
Will a Viair 20005 (2 Gal tank, 280c compressor, 110-145 PSI switch) 1/4" line & Wolo 804EV solenoid take care of business? I was told this setup is sufficient for these horns.
Thanks for any additional input!

Look at the dimensions to see if you have room for the 1056 Twin Connected - it's a big package. (I went and looked at the Catalog this time - I could have sworn there was one size bigger...)

If you go for the solenoid valve you can use the regular horn button, but remember that it's then "all or nothing" - and you always have the hazard of the switch being set the wrong way.

The nice thing about a Lanyard Valve is you can modulate the volume and throat of the horn like a train horn. You can get anything from a little squeak to get someone's attention to a WIDE OPEN "I'm coming through, and you'd best get out of the way!" And there's no confusion when you reach up and pull.

A small compressor and 2-gallon tank will be fine for short bursts, but you can easily outrun your air supply if things are going seriously wrong. If you can find room for a larger tank under the truck bed, I would do that first thing - it's a lot of work to redo later, but will give you a nice long blast - with a long recharge wait...

You can get larger 3 and 6 gallon "hot dog" tanks meant for truck air brakes from a truck parts supply, and I would get the 'remote lanyard pull' water drain valve at the same time so you don't have to crawl under.

The compressor is usually tucked in under the hood to keep it dry (or drier...) and a short run to the battery - they are easier to upgrade later. If you are using the "oil sender" size pressure switch that comes stock, put a relay between the battery and the compressor, it will last longer.

If you have problems with compressor hard starts, convert over to a regular compressor duty pressure switch with an unloader valve - you need to put a check valve where it feeds into the tank, then connect the unloader valve to vent pressure from the compressor to tank line.

If you want to go crazy on the compressor and can figure out a place to mount the monster, Gast and Thomas make them up to 1/2 HP - 12VDC 52A full load. 150 PSI max. Grainger.

--<< Bruce >>--

Thanks for all the advice and info guys!
I'm still a newbie at this but got a lot of info from Train man and Kim Pederson.
I went with Air Horns of Texas for my kit. May or may not be the cheapest option, but I'm fine with what I got.
Got the 1054 and 1055 horns. The 1056 is apparently what's used now on the Mark VII's, seems to have a slightly higher tone than the 1054-1055 combo, but I'm happy with the classic sound. Also, mounting these LONG horns in a car is easier when they are seperate, more mounting options. I'm using a Viair 20005 tank/compressor combo. Has a 110/150 PSI switch, 30 percent duty cycle, 2 Gal. tank.
Just started on the installation process. I did a temporary rig-up on my driveway with the whole setup outside the car just to hear it, and WOW is it LOUD! Just did a couple HONK HOOOONKS, and I had my neigbor coming outside to see what was going on.
So can't wait to complete the install, here's some picture and video links for what I've done so far. The zip ties are obviously just a temporary trial fit on the horns.
Any additional advice is appreciated!

Photos of trial fit:
http://www.flickr.com/photos/14890460@N02/6328370908/

http://www.flickr.com/photos/14890460@N02/6328371418/

http://www.flickr.com/photos/14890460@N02/6327619571/

http://www.flickr.com/photos/14890460@N02/6327620069/

http://www.flickr.com/photos/14890460@N02/6328372960/

http://www.flickr.com/photos/14890460@N02/6327621343/

And my outside the car horn test. Audio here does no justice to how LOUD it really is!
http://www.flickr.com/photos/14890460@N02/6328334964/

Bruce,
Thanks for your info also!
This is not a typical install on a truck, as you can see from my pics.
This is being installed on a '97 T-bird, which makes the room an obvious issue.
I'm not worried about long bursts, or repeated honks daily.
I just want to be able to occasionally let out a few honks here and there, especially when I pull into the Disneyland parking structure!
Can't wait to give the cast members and guests in there a little 'Whoa, I know that horn'!

That is NOT the time or place to play with a truck horn, They Are NOT A Toy!!

The Mickey & Friends Parking Structure entrance plaza is an echo chamber with the 15' concrete ceiling, and the Resort Transportation & Parking CM's are not wearing hearing protection in their booths, not to mention the other cars with their windows down and right next to you. Blown eardrums (and an attitude about "Yeah, I did it, what are you gonna do about it?") could be turned into an assault charge...

You might be able to control the volume well enough with a manual lanyard pull and/or the pressure to the horns turned way down with an inline pressure regulator to where they just voice clearly (Hint: Like on the Monorails themselves) but DO NOT TRY IT with a solenoid valve at full system tank pressure, when it's all or nothing. I wouldn't chance it, at full voice those suckers are Loud. Which is the whole reason why you're installing them.

Save the air horns for when you need to send a real safety message on the road that will get through car windows and overpower loud stereos.

The relevant sections below, color emphasis mine. (Fire Trucks use the StutterTone horns, you don't want that one.) If you don't go around blowing them unnecessarily it won't ever be a problem - but if a Cop wants to "teach you a lesson", he has the Lesson Plan in law.

We have a Blooming Idjit around here somewhere (West San Fernando Valley, Simi, Thousand Oaks) with a full-on set of (sounds like Nathan K5) Train Horns on his car/truck and he's sneaking up behind people and letting loose a full-on long blast trying to startle someone into an accident, right turn and into parked cars or the side of a house... The cops and many concerned folks are actively on the lookout for him. (Most people are too rattled to look around and get descriptions and license plate numbers.)

First order of business when they catch him is "Do you have a receipt for those horns?" since they are easily stolen off a parked locomotive left on a siding. The railroads keep a record of the serial numbers and will prosecute for grand theft - and the Feds can get involved since it's tampering with Safety Equipment of an Interstate Common Carrier, and those will hurt a whole lot more than a little moving violation ticket.

--<< Bruce >>--

Horns or Warning Devices http://dmv.ca.gov/pubs/vctop/vc/tocd12c5a1.htm

27000. (a) A motor vehicle, when operated upon a highway, shall be equipped with a horn in good working order and capable of emitting sound audible under normal conditions from a distance of not less than 200 feet, but no horn shall emit an unreasonably loud or harsh sound. An authorized emergency vehicle may be equipped with, and use in conjunction with the siren on that vehicle, an air horn that emits sounds that do not comply with the requirements of this section.

(b) A refuse or garbage truck shall be equipped with an automatic backup audible alarm that sounds on backing and is capable of emitting sound audible under normal conditions from a distance of not less than 100 feet or shall be equipped with an automatic backup device that is in good working order, located at the rear of the vehicle and that immediately applies the service brake of the vehicle on contact by the vehicle with any obstruction to the rear. The backup device or alarm shall also be capable of operating automatically when the vehicle is in neutral or a forward gear but rolls backward.

(c) A refuse or garbage truck, except a vehicle, known as a rolloff vehicle, that is used for the express purpose of transporting waste containers such as open boxes or compactors, purchased after January 1, 2010, shall also be equipped with a functioning camera providing a video display for the driver that enhances or supplements the drivers’ view behind the truck for the purpose of safely maneuvering the truck.
Amended Sec. 27, Ch. 945, Stats. 1997. Effective January 1, 1998.
Amended Sec. 2, Ch. 166, Stats. 2005. Effective January 1, 2006.

27001. (a) The driver of a motor vehicle when reasonably necessary to insure safe operation shall give audible warning with his horn.

(b) The horn shall not otherwise be used, except as a theft alarm system which operates as specified in Article 13 (commencing with Section 28085) of this chapter.
Amended Ch. 993, Stats. 1977. Effective January 1, 1978.

I believe it. I've heard first hand numerous times the prototype system installed in Kim Pedersen's Ford Taurus.

I'm thinking...

If you go with the install that way, you could solve the Volume problem with two solenoid valves - One that lets full pressure through, and a second solenoid valve with a full-size 3/8" pressure regulator in front of it, adjusted to that nice mellow "woot".

That would be the button you hit to play with in the parking structure, or to warn pedestrians on residential streets. Don't use the "Mini" 1/8" pressure regulator that's machined out of 1-1/2" aluminum bar stock, the real cheap ones use a Schraeder tire valve core for the poppet valve and simply can't flow enough air - likely to sound more like a strangled goose...

You put the flip-up switch cover over the Full Blast switch.

--<< Bruce >>--

I know exactly who you are talking about, but I haven't been able to catch his plates. He's blown that thing in our neighborhood in Simi Valley and scared the bejesus out of my 81 year old mother-in-law. Of course it doesn't help when there are numerous youtube clips out there that glorify these kind of horn pranks.

Bruce,
I'm sorry you got the wrong idea about me. I have no intention of letting out a full blast in ANY parking structure. I was talking about a small toot, at a safe distance from peoples ears. I know these horns are not toys, and I am not installing them the scare ANYONE, believe me. The whole idea is to have a horn that sounds like the Disneyland Monorail, and I will install a pressure regulator for just that reason.
Thanks for your added advice on the regulator!

Hey Bruce,
any suggestions on where I could find a good pressure regulator of this size, without being too expensive?