Dieter, I seem to remember Ron Hast saying they had six matching Eureka 3-Way Landau coaches in '62, but my recollection may be wrong and Allan Abbott would certainly know better than I. Regardless of the number, I do not believe Abbott & Hast kept any record of which car from the fleet was used for Monroe's service.
I'll echo the sentiments of others in that TPC #159 is another fine effort from the team! While I greatly respect Tom McPherson as an author, the use of the term "Landaulet" throughout the Eureka article struck me as incorrect... Certainly from an automotive terminology definition, but more so due to the fact that Eureka never referred to their Landaus as "Landaulets", at least to the best of my knowledge. Nonetheless, a very well written an enjoyable article!