P for "Pool". Between 1969 and 1977, 353 steel cupola cabooses were modified to operate system wide, in what was known as "pool service". This included interchange on run-through trains with SP, C&NW, CB&Q (later BN), and CRI&P. Since the only correct steel cabooses that are generally available to us N-scalers are Intermountain CA-3's and CA-4's, two CA-3's (25012 and 25049), along with seven CA-4's (25112, 25125, 25133, 25176, 26181, 26190 and 25193) were modified for pool service in 1975. Of course, the most obvious indicator of "pool service" was the big red "P" on all sides of the cupola, but also safety slogans and bigger Scotchlite lettering and other graphic differences, including red Scotchlite around the top of the cupola were also very noticeable.
Actual mods to the car itself were many, including a radio, oil stoves for heating, a complete water system, and roller bearing outside swing-hanger trucks. An axle-driven alternator was also included to support the added electronics, and the new electric lighting, electric refrigerator, electric end-platform marker lights and the new electric red-over-green marker lights on the front and back of the cupola.
Also quite noticeable were the Lexan polycarbonate safety windows in the sides and ends with rounded-corner black rubber gasketed adapters on the body ends and front & rear cupola sides of many modified cabooses, but not all pool service converted steel cabooses got the adapters, and they retained their square windows. Cupolas also had wind deflectors on the side windows, with some cabooses having a single centered deflector (CA-8's and CA-10's) and others having deflectors on both the front and rear sides of the side cupola windows (CA-7's and CA-9's). I can't find any info on pool service CA-3's and CA-4's as far as deflectors are concerned, but several photos I have show plainly they had two deflectors per side.
Not noticeable except by the crew, were new, federally approved retention toilets.
Along with the new oil stoves, some pool service cabooses also got a taller, larger diameter smokejack, with horizontal bracing attaching it to the cupola. Others retained the standard wire bracing.
Notable is that not all U.P. cabooses got converted to pool service, many retaining the smaller lettering until they were retired. Many cabooses, both pool service and non-pool service, retained their running boards and ladders too, even when it was federally required to remove them.
Most non-pool service steel cabooses eventually got the pool-service treatment, excluding the Scotchlite lettering and the Lexan safety windows, with no CA-6's ever being actually run in pool service.
Just for fun, what I do is find photos of specific cabooses, and I model them...with all their differences from each other. My era is from 1947 through 1956, so differences in U.P. cabooses in my locale and era are different than what you'll get if you're modeling a later era.
For those who are modeling the U.P. during an era that ran cabooses, the book "Cabooses of the Union Pacific Railroad" by Don Strack and James L. Ehernberger is an absolutely invaluable resource. There is updated information about all things U.P. in Utah, including cabooses on Don Strack's website here:
www.utahrails.netCheerio!
Bob Gilmore
