Looking at some K3’s on ebay I keep reading about how they claim to have the older better version compared to the new “toned down version”.
Whats the story behind this? If its true there are two different versions, how do I tell them apart?
The real old ones are sand-cast not die-cast. They will have a little mellower sound. Other than that, when it comes down to it, the newest ones have better quality control, so the bells are closer and more consistently in tune.
they also have an “over the road” version. Has like an inlet reducer in it that restricts the air…still loud though.
no, we dont want our horns reduced in noise volume… 
thats why we get them… to make noise.
Hmmm, is that in the manifold or in each horn?
i believe it’s in the manifold…i think the restrictor can be removed though.
So basically you only want to invest your money in the old casting horns if you are a collector,they go for more money because hardcore collectors are willing to pay top dollar for them.If you are looking for a set to do a install with go with a newer set of horns.Newer horns are going to last longer and give you less trouble down the road…
Sound wise I can’t really tell them apart with my ears, they are really close. I try to stick mostly to Newcast unless I’m in it for collecting. Less cast defects too.
I like cast defects lol they give horns more collectibilty to me. If you want to compare tones in K horns, listen to a recording of a Chessie K5LA and just one on somebody’s truck. You will definitely be able to tell the difference. Another good ear test for ya is to listen to a new cast P5 and an old cast P5. That’s the biggest difference in sound in old vs. new I’ve ever heard.
I know this is off topic since you were referring to the restrictors in the “Over the Road” horns but as far as I know they can be removed with an allen wrench and they are in the base of the manifold.