Your quest for "the man who built it" is a bit fuzzy, but, according to a history book for Indian River County, Florida, in 1919 Vero Beach's first schoolbus driver, Leon B. Gollnick, had the contract for transporting district school children. Accordingly: "He purchased a new Oldsmobile truck and added a body.....". From this it isn't entirely clear if he bought the chassis and added a prebuilt body, had a custom body added, or if he actually built the body himself. Whatever the case, I assume that Leon B. Gollnick is the name that you are looking for.