Corgi Truck & COA from Horsepower Gift Set
The Giltedge Horsepower Gift Set included a Hackney in Gold Florentine and a die-cast metal Series B Mack truck made by Corgi, and a COA. They were only available to "Just About Horses" subscribers as a Special Run set in 1996. The truck features Breyer's colors, logo and even the old Chicago address, making it a beautiful, high quality accessory for any collection, whether you have the horse or not.
According to IDYB, there was a shortage of trucks and about 200 sets were missing trucks when shipped, so buyers were offered a calendar instead. That makes the trucks even harder to find today.
Breyer Model #703956 (truck model #98453)