This style I believe where all Forged and the lightest. Easiest way to tell is take a peak inside, you'll see they are made by Alcoa in the USA (There is part numbers in other threads)
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Series 1 Forged ^^
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The Series 2 versions above are where it gets murky. The late Series 1 models are Forged, from what I heard the demand exceeded the supply for them in production (In another thread it mentions the factory got so backed up with cars waiting for the rims, they resorted to getting stock via air freight from the US, which would have cost a small fortune) but for VF2 onwards the bean counters made em switch to cast. In saying this there was scattered reports that people with VF2's got the forged from the factory, but ex Holden workers mentioned this not to be the case so not sure here
Externally, they are very similar on the face, but the Forged versions have a thinner spoke. Again, easy way to tell is look inside the rim, it will say Alcoa.
They also differ in the internal section of the rim, the cast versions are more flat and fully painted black, where as the forged are only painted on the face and inside, not the internal section (See below, on the cast this bit is all black).
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Alcoa markings. On the cast versions, this will just have a GM, manufacturing date and Thailand stamped near the hub on the back of the spokes. Weight difference is about 2.5Kg, but I haven't been able to clarify if this is compared to the more common series 1 rims I posted first
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