JMHO
If you do a comparison of the right side units side by side the cylinder #2 primary tubes look to be a different configuration....no?
Is it possible they somehow got a hold of the other header pattern? I seem to recall Watson and Jeal, or something like that? I would think there could be small differences between the two competing original header designs from way back when. I must admit I do not know enough about LT5 headers so I may be way off base here. Sorry.
Tom