We've searched the internet and found the largest collection of On30 Scale trains for sale is on eBay. Below are the listings for 'Rail Truck'.

ON30 RAIL TRUCK CONVERSION KIT MOW CAB FITS BACHMANN RAIL TRUCK
ON30 RAIL TRUCK CONVERSION KIT MOW CAB FITS BACHMANN RAIL TRUCK
$30.00
Time Remaining: 2d 16h 18m
Buy It Now for only: $30.00
ON30 RAIL TRUCK CONVERSION KIT FREIGHT CAB FITS BACHMANN RAIL TRUCK
ON30 RAIL TRUCK CONVERSION KIT FREIGHT CAB FITS BACHMANN RAIL TRUCK
$30.00
Time Remaining: 2d 16h 18m
Buy It Now for only: $30.00
ON30 RAIL TRUCK CONVERSION KIT PASSENGER CAB FITS BACHMANN RAIL TRUCK
ON30 RAIL TRUCK CONVERSION KIT PASSENGER CAB FITS BACHMANN RAIL TRUCK
$30.00
Time Remaining: 10d 17h 2m
Buy It Now for only: $30.00
Bachmann Spectrum On30 Rail Truck 29133 US Mail NIP DCC on board
Bachmann Spectrum On30 Rail Truck 29133 US Mail NIP DCC on board
$127.96
Time Remaining: 28d 17h 18m
Buy It Now for only: $127.96

Other On30 Scale train items recently purchased through this site:

ON30 RAIL TRUCK CONVERSION KIT MOW CAB FITS BACHMANN RAIL TRUCK
ON30 RAIL TRUCK CONVERSION KIT PASSENGER CAB FITS BACHMANN RAIL TRUCK
ON30 RAIL TRUCK CONVERSION KIT FREIGHT CAB FITS BACHMANN RAIL TRUCK
Bachmann Spectrum On30 Rail Truck 29133 US Mail NIP DCC on board