I did not know that yesterday!

UPS currently has over 88,000 "Big Brown" delivery trucks in its fleet, all with no visible manufacturer logos. Why? Because every design aspect of the UPS truck, from the hubcap to the tail light, is proprietary.

After several fruitless searches through the official UPS site, I stumbled upon a chat room at Automotive Helper that suggested UPS trucks are built by an automotive manufacturing firm called Grumman Olson. An unofficial corporate history of Grumman seemed to back this up:

"1966 - Grumman teams up with UPS to develop the now familiar UPS P-600 and P-800 truck bodies, featuring lift-up fiberglass hoods and translucent fiberglass roofs." We found supporting evidence at the truck photography collection of James Cox. Note that Grumman Olson only provides the truck bodies; the components likely come from a variety of places.

In other exciting UPS news, the brown trucks will be making their video game debut in "NASCAR 06: Total Team Control." That's right, you'll be able to steer Big Brown around the racetrack.