I've seen laments around the web that vehicles in 1:48 are hard to find. So it came as a surprise to me that one source could be my local Menards (a Midwest USA home improvement store).
While browsing their collection of "O Gauge Train Stuff", I found what appears to be a decent representation of a Mack Type R (or one of its variants). The Mack R-series was produced between 1966 and 2005. I don't know exactly which year this particular model is patterned after, but at a glance it would appear to be of 1970s of 1980s vintage (mainly since there aren't any rounded corners).
Some of the details look a bit chunky, but it says 1:48 scale on it and, heck, for $6.99 USD, it would probably serve as a starting point or at least a stand in. Schutte Lumber wold need some delivery trucks.
There's also a delivery van and an ambulance, but they seem to be a bit new for my era. The van is a later Chevy model and the ambulance is a Ford F350.