look at your fronts and rears look closely at the outer lip. on the front you should see where the outer lip tucks into the outer edge of the wheel if you follow that around there should be a spilt on the outer ring as in the frist picture. On the rear since the wheel (assuming all 6 are in place) you will have a solid outer edge no where for the outer ring to tuck into the wheel as it is all one piece on that side. By 70 i don't think they were using widowmakers any more (as original equipment)If your wheels have a solid lip all the way around and there is no way for the outer ring to tuck into the outer edge of wheel on either side. look at the flat portion if there is a raised part similar but sharper than that of a tubeless wheel you may have widow makers you have to look very close where the the squared off center raised section is tosee how they lock. I have proably just muddied the waters more than ever. enlarge the pictures of the wheels I posted as best you can and they may help