I love treadling my 15-90 that I de- electrified (is there such a word...ha ha)!!! She was originally an electric machine. I had a singer 66 treadle. I switched the 15-90 to the treadle base. And put the 66 into the 15-90 cabinet. Thus, essentially I now have a 15-88. I also love treadling her. She is my go to machine...always "on" and ready and never complaining. She looks exactly like your pic but with 6 drawers. I feel like I get a little bit of a workout treadling...burn a few calories while I sew.
Kathy
Near the WI-IL border