Mike, I'm not familiar with the spaceliners, but very familiar with the Bendix kickback 2 speeds. I didn't see any of your posts as to what year you have but if you want to make it correct 60 -64 would be a red band, 65 - 70 would be yellow. Either will work, same gearing in both but some of the internal parts are different. The 2 speed parts wont go inside the single speed hub so you will have to re lace the wheel,... and probably need a different length spoke. And yes you can test it in your hand. If its not to gummed up hold the brake arm and spin the sprocket. Watch to see how fast the hub is spinning. Now spin it back like applying the brake then forward again. The hub should spin faster or slower depending what gear it was in. Lots of info out there on the bendix 2 speed kickback hubs, you'll probably find more in the Schwinn forums.