We would need specifics... there are many editions for the Polar Express and many MPC Hudsons and Tenders...
Basic Tender Families Families:
- Square Santa Fe style tenders based on the 233/243 Postwar Tenders that are 7 5/8 long
- Small Streamlined 200 series tenders that are 7 1/2 inches long
- The Streamlined Tenders that are 8 1/2 inches long (Think 2046W)
- 8 Axle Version
- 12 Axle Version
- The Die Cast Tender that is 8 1/2 inches long (Think 2426W)
- Early Coal Tenders (Think 2466W)
To further complicate things, even if the mounts interchange, the whistle housings may be of different dimensions and cause interference.