There is a similar rationale for the numbering of the WW&F's replica caboose no. 320. The original railroad had one true caboose (301) and three additional waycars that functioned as cabooses (302-304). However, numbers 305-319 on the original railroad were occupied by boxcars (including surviving boxcars nos. 309 and 312), so when the replica caboose was completed in 1998 it was assigned the next available number in the 300 series, namely 320. As Brian Norden so aptly put it, we honor the history of the original railroad by not re-using the numbers of original equipment that is no longer with us.
-Philip Marshall