Russ,
Living in CT, I'm not sure what a "cow and/or sheep car" sounds like. I would imagine that it would sound like the basic freight car minus some of the clanks and bangs, plus some Mooo's and Baaaa's.
I can certainly try to put a sound track together to try it. I created the Boxcar Loop using public domain sounds and built the loop by putting each type of sound on a different track, like a recording of a band's music. That allows me to adjust the clickety clack, brake squeal and clangs & bangs volumes separately on the final "mix". I notice the brake squeal sounded the same over and over so I changed the frequency so that each squeak is higher or lower pitched... more random and realistic.
I'm guessing that a bunch of cows (are they called a herd if they are in a cattle car?) would have a variety of "voices" so it doesn't sound like the same cow moo-ing over and over!
You have me thinking about it now....
Trying to pin down a price for the "ed-assembled" unit (but no car)... probably between $60 and $75.
If anyone sends me an email indicating an interest, I will send details right after York week!