Spitfire Frame Interchangability

[Nolan Penney <npenney@erols.com>]

Here's my delema, my 1980 Spitfire frame is in less then rust free 
condition.  Every time I go under that car I keep finding new holes in 
the frame.

I've got a 1974 parts car sitting out back, with a much better looking 
frame.  Hmmm.

So, can I put a 74 frame under a 1980 Spitfire?  I'd thought they used 
the same frame thoughout production, but a friend told me they made some 
significant changes in the 1500 Spitfires.