It served the Grand Trunk Western Railroad by pulling various heavy freight and passenger trains across the Lower Peninsula of Michigan and Northern Indiana.

6323 was constructed in February 1942 by the American Locomotive Company in Schenectady, New York as the twelfth member of the Grand Trunk Western's U-3-b class.

The U-3-bs were a class of 4-8-4 "Northerns"(or "Confederation" types as sometimes referred to by the GTW) that were primarily used for fast freight and passenger trains.

6323, in particular, was mainly assigned to pull the Maple Leaf passenger train between Chicago, Illinois and Toronto, Ontario in Canada alongside the GTW's streamlined U-4-b locomotives.

It was also often seen pulling mixed freight trains across the Lower Peninsula of Michigan and Northern Indiana.

6323 subsequently spent over two decades on static display outdoors while receiving some cosmetic touch-ups as time flew by.

6323 still on indoor display at the IRM, and it is also awaiting a future cosmetic restoration to become more presentable to the general public once again.

6323 holds significance for being the very last operational steam locomotive on the Grand Trunk Western's active roster.