Was this part of a set?

Yep.  I believe it came from the set linked below, circa year 2000:

https://www.lionel.com/product...m-loco-4000-6-21989/

Thanks Ted. S, that is the set with the cars I have.  Interesting that Lionel got it right, the CB&Q did run 4-8-4's.

Well, maybe Lionel got it right.  The produced set was actually a 4-6-4, and I think those were primarily used as passenger train engines..

Chuck

@PRR1950 posted:

Well, maybe Lionel got it right.  The produced set was actually a 4-6-4, and I think those were primarily used as passenger train engines..

Chuck

I came down with a case of Whyte Dyslexia seeing 4-6-4 and looking up and typing 4-8-4, thanks for pointing that out.  Buuuuhut... if Lionel did mark a 4-8-4 for the CB&Q, they would have been right too.  Something the road names on their Adriatic seldom got right except for 'Lionel Lines'  Don't get me wrong, I love the 2-6-4 and have  5 of them,  I'm like Mel Gibson in 'Conspiracy Theory' where if he saw a copy of 'Catcher in the Rye' he had to buy it, I can get the same way for that lowly engine,  plus it is pretty much a bullet proof loco.

Incidentally, at least 3 of these cars were also available as separate sale items: the #26112 Gulf tank car, #16446 hopper, and #19784 caboose. While Lionel has done several similar Burlington boxcars, that particular one may have been unique to this set.

Thanks breezinup, those are the numbers that are not imprinted anywhere on those cars, and guessing the box car will remain a mystery.