Thanks for all the suggestions. I did find the brass track on the Bachmann website. I have since found out that a 5 ft diameter will work.
I also found a work around. The locomotive has two guide pins inside the center axle presumably to keep the center wheels engaged as it rounds turns. I remove these two guide pins and the locomotive now works fine on regular Bachmann curve track. The center wheels do run on the edge of the track on curves but there is enough engagement from the other two wheels to keep it moving. Not the best arrangement but it works well. Much better and cheaper than the alternatives.
Once again thanks for your information.
Bill
I also found a work around. The locomotive has two guide pins inside the center axle presumably to keep the center wheels engaged as it rounds turns. I remove these two guide pins and the locomotive now works fine on regular Bachmann curve track. The center wheels do run on the edge of the track on curves but there is enough engagement from the other two wheels to keep it moving. Not the best arrangement but it works well. Much better and cheaper than the alternatives.
Once again thanks for your information.
Bill