5 speed questions
Is the spacing (OLD) 120, 125 or either? If 5 speed freewheels can work on 120 OLD hubs, could a freewheel be attached to a track hub? Let me know if this question makes sense. Thanks y'all.
Your question isn't really clear. Road bikes designed as new for 5-speed freewheels or Ultra-6 freewheels, dating from at leas the '50s through around 1980 or so, had 120 mm OLD. If they were designed for standard 6 or higher, they were 126 mm OLD. Some may have been 128, but I'm not sure about that.
I don't expect the 5-speed will work on a track hub with 120 spacing, even if the mechanical interfacing works.