This model was rebuilt originally by the late Bill Johann, came to me second or third hand after his ownership. It is an Eastern car that was nicely built up, I believe likely lettered with decals over painted over printed sides, then painted over yet again and lettered for the Rutland.

A very nice article on building models of this car in HO is online, and opens by noting that

Pullman Standard’s PS-1 box Car is THE iconic piece of rolling stock that defined the vision Rutland Railway president Gardiner Caverly laid out for the railroad in the early 1950’s, that of a modern, streamlined, service-oriented gateway that would rapidly move shippers products to market.

Bill Johann was an American OO operator and over the years updated his layout to the modern era; I own a number of these models today. Based on the markings I believe he probably converted this car to Rutland in 1971 and then modified it to a more modern appearance in 1994; when it came to me it was on roller bearing trucks and had no roof walk and an ACI label.

The Rutland shut down in 1963 and the use of ACI labels began in 1968, so this was problematic to my eye. But such a nice car, I did want to run it. What I did was paint over the ACI labels, add a roof walk, and put it on Schorr trucks. The roof walk should be painted the color of the roof but I opted for black (to match the ends) and made it from two HO roof walks spliced together.

It is not quite a PS-1 boxcar but it is a very good stand in for this iconic car, I am enjoying running it on the layout.

UPDATE: The model has been updated further, see this article.