So there was a discussion recently here.
About non-defrost glass as being fitted to early 240z's delivered in the US (maybe 1969 dated cars?) but interestingly Nissan gave all HS30's delivered to Australia no defrost options (or it was an option but I've not seen any 240z's in Australia with this glass) up until the 1974 260z which didn't get the sexy vertical defrost glass, instead they got the horizontal lined glass.
Anyway this was tough to photograph in the dark of a garage but this is the glass out of HS30 00150 a 1970 delivered HS30. As you can see it has the stamp M-214.
The early US cars with clear glass (and no defrost) have the code M-214 and later cars with tinted glass (and defrost) have the code M-224 according to MikeB in the other thread.
Personally I've always liked the vertical defrost glass look.
The orange on the right is from an old sticker / emblem.