* Delete 2 Part bb0037 Black Train Brick 2 x 4 x 1 1/3 Sliding Block with Wheels Holder
* Add 2 Part bb0037b Black Train Brick 2 x 4 x 1 1/3 Sliding Block with Wheels Holder, Type b with Ledge
* Delete 2 Part bb0037 Black Train Brick 2 x 4 x 1 1/3 Sliding Block with Wheels Holder
* Add 2 Part bb0037b Black Train Brick 2 x 4 x 1 1/3 Sliding Block with Wheels Holder, Type b with Ledge