Train horns???

[Dreamweaver]

When you are dealing with Inter-Species parts like this don't worry about what the scale of the part is.

I have parts that are for 1/8 cars that are right on scale for these trucks.

I'd look for either a G scale horn or an S scale horn. Get one on you might be surprised.

Like I said I have parts from 1/8 scale cars like windshield wipers and door handles that fit these trucks perfectly. A 1:1 car is much smaller than a 1:1 truck therefore its parts are smaller. If you use a larger scale part then the scale comes out right. Trains are much bigger than trucks, same thing works in reverse.