Kevin:
I've had good luck with decal paper for an inkjet printer, followed by a couple of light coats of artist's spray varnish to keep the ink from running. Just be sure you DON'T use a water-based varnish. Here's a link to the FDNY logo: http://www.fdnysmart.org/wp-content/uploads/2015/04/fdny-logo.png.
Also, if that works for you, here's a link to the E274 logo from the Mack era . . . https://img.auctiva.com/imgdata/0/3/2/5/5/9/webimg/988113966_tp.jpg
Good luck!