few weeks ago I started to model the MPSB No 240 boxcar and had proudly present it at the 0scale NG meeting in Wulften/Germany last weekend. The MPSB (Mecklenburg-Pomeranian Narrow Gauge Railway) ran on 600mm (23 1/2") gauge and was the largest railway of this gauge in Germany. Similar cars I found in an old O&K catalogue, they were delivered to Mexico.
Here are some pics:
with 12 mm standard TT-bogies, at the moment I'm waiting for better ones from Malcolm Savage...
with 16.5 mm H0 Kadee's, they have just the right dimensions except the gauge, compared with a Fleischmann 0e van (750mm/30" gauge).