QUOTE: Originally posted by Train 284 The main difference bettween O and On30 is that O scale runs on three rail and is larger and is usually modeled in standard gauge, not that there is not any narrow. On30 is smaller and runs on HO gauge track, but is slightly larger than most HO equipment, hope that was enough info. Let me know! ya!!! that helped alot i really appriciate all the help you have given me!!![:)] keith Matt