The link below is about 8-lug wheels,... but it's good info on installing "early" hubcaps on later model wheels.
http://www.laroke.com/larryk4674/smo...er/hubcaps.htm
Here is a picture of a stock
6-lug clip style wheel.
I believe these were pre-'61 wheels.
(or had a mid-year change in the '61 model)
Anyone know for sure?