Nice work Lee.
I am installing more of the YLB 10510 Batteries in my Lionel Pennsylvania H10 steam engines. It is a tight fit in the #1773 low tender. The Pennsylvania H10 #7109 has a little more room in the higher tender. The Western Allegheny with the high tender should be the same. The power wire needs to be spliced into the gray center roller wire on each of these engines.
I am going to contact Lionel for longer arm pick-up rollers. All three Legacy H10 engines stall at slow speeds on my #5 switch at the Village of Deichman.
I put a YLB 10510 in my Southern Pacific #4449 this afternoon. It pulled 10 passenger cars around the layout without any sound drop-off.
Sincerely, John Rowlen