All 4 that were announced can be found here:
MTH adds a black water tender to its recent announcement - perfect for your Big Boy!
- MTH 20-3858 - Auxiliary Water Tender I "Union Pacific" #907853 (Hi-Rail Wheels) - Sale Priced at $249.95
Here are the others already announced:
- MTH 20-3855 - O Scale Premier Auxiliary Water Tender I #809 (Hi-Rail Wheels)
- MTH 20-3856 - O Scale Premier Auxiliary Water Tender I #814 (Hi-Rail Wheels)
- MTH 20-3857 - O Scale Premier Auxiliary Water Tender I (Hi-Rail Wheels)