Marty
Despite the thousands of models of extended vision UP cabooses that have been made in all scales over the years the UP never owned an extended vision caboose.
My first O scale UP caboose was an extended vision caboose too. That was before MTH and Lionel came out with their CA-1 and CA-3/CA-4 models in the mid 2000s.
When other railroads were buying steel cabooses like the International Car standard and extended vision types the UP stuck with their own design that was used for their CA-3 through CA-10 classes of caboose.
The CA-11 and CA-12 were UP custom design bay window cabooses that have not been made by a major O scale manufacturer.
The UP only had one class steel cabooses built to a standard commercial design. The UP purchased 130 bay window cabooses between 1967 and 1970 and leased them to the Rock Island. When the Rock Island went bankrupt in 1980 the cabooses were returned to the UP and Classed as CA-13s. The Atlas Trainman, K-Line, Lionel and MTH bay window cabooses all approximate the UP CA-13 class caboose.
And on the other side of that coin, no other major railroad ever bought steel cabooses built to UP designs. So all those CA-3 and CA-4 Lionel cabooses in eastern railroad heritage schemes are just as much a fantasy as their pain jobs.
The same goes for MTH CA-1s in several road names like SP&S or NYC. The SP did have a large number of cabooses built to a "Common Standard" shared with the UP in the Harriman era and the MTH CA-1 is a good representation of those SP cabooses.
In the case of both Lionel and MTH I think they use fantasy paint schemes, like Heritage scheme freight cars, to put some mileage on tooling for less common models.