Will a 1979 Camaro rear end fit 1967 Camaro?

No, a 1979 Camaro rear end will not fit a 1967 Camaro without significant modifications, if at all. The chassis, suspension, and mounting points are drastically different between those two generations. The width, spring perches, and overall geometry are incompatible. While some parts *might* be adaptable, it would be a major undertaking requiring fabrication and custom work, far beyond a simple bolt-on swap.