55,
I can't tell you with any confidence about the earlier versions, but all of the Novas from 68 - 79 were uni-body cars with subframes.
Just in case you're thinking about using the subframe in another vehicle, double check the width. There's a pretty good difference in the width between the subframes used in the late 60 - early 70's and those used in the mid to late 70's.
