Hi Dan,
I am not the Bach-man, but I can tell you that the P&C Caboose you want was first in the catalog in 1998 and was the logging caboose which has the flat roof with no coupola. It was not a great seller and was in the catalog only til 2002 and was not rerun.
If you can find a Bobbber caboose on Ebay of the logging type it will be easy to swap out the roof.
This caboose has the correct roof for the P&C caboose, but is way overpriced:
http://www.ebay.com/itm/4-Wheel-Caboose-Paul-Bunyan-Logging-G-scale-Bachmann-/121997729583?hash=item1c67a19f2f:m:muR8B8GzjTFv3QEGf2I4qxgIf a coupola roof is OK with you you can go ahead and buy any bobber style with a coupola and add the roof to the P&C caboose assuming you win the P&C caboose.
This one has all you would need to replace the roof and it has the grab irons missing on the P&C caboose:
http://www.ebay.com/itm/Santa-Fe-Caboose-with-steel-wheels-and-Lighted-Lantern-/182464154892?hash=item2a7bb60d0c:g:0usAAOSw2xRYiNzsTh only down side is that the coupola on this one is red while the color of the P&C caboose is Boxcar red or Tuscan Red. A little paint from the hobby store would solve that issue.
Or you can just wait it out and keep an eye out for a reasonably priced bobber with a flat roof.
Hope this helps.
Loco Bill