Early 240z's would not be drastically lighter than later ones or even 260z 2 seaters for that matter. Yes later body shells would weigh a bit more due to air con being fitted and perhaps more accessories etc.. and more structural rigidity in the frame rails and rear strut towers etc.. but I doubt it's a huge difference.
It all depends what cars you're comparing too. A 280z with big bumpers and fuel injection or a home market late s31 with electric windows, mirrors etc.. and slim bumpers but fuel injected.
Where I suspect the lighter "240" shells idea comes from is confusion around the Z432-R shells and some of the works rally shells getting the same treatment in terms of thinner panels but strong in terms of frame / support sections etc.. some of these cars had HS30 and HLS30 prefixes where as the PS30-SB was the Z432-R of course.
Mostof these cars were not generally available to Joe public and many of them got binned and are simply not around anymore anyway.
For AU market cars I'd be very surprised if an early 240z weighed much less than a 73 240z.
Finally managed to get the 240Z off the rotisserie.
We have a issue were the front discs are a little too big and the SW front bracket is short for the R33 calipers so the two dont meet. The rear calipers fit good and there is good clearance for the wheel to spin freely. Will need to sort out possible smaller discs for the front. Anyone had this issue before?
Have seen a few videos on the Sport-Design, really nice fit and finish from what I can see. Price is a bit ambitious for what you're getting in my opinion, did a quick conversion for their 2.9L Sport-Design - $155,000 AUD! That'd be before delivery fees and shipping. Don't want to even think about what they'd ask for a stroker.
Do wish them best of luck though, I'm sure there's a market for boutique Fairladys. Plus this likely will lead to more companies producing nice bits for our Z's.
I've seen that figure thrown about a bit - likely relating to the extremely early build numbers with thinner sheet metal. Might be completely wrong though. Would have to ask someone like Gav for more info. If mine weighed 1070kg dry I'll be under the 1000kg dry mark relatively easily.