Will a 85 camaro rear end fit in 70 Chevelle Malibu?

No, a 1985 Camaro rear end will not fit in a 1970 Chevelle/Malibu without significant modifications, and it's likely not practical to do so. The mounting points, width, and axle design are substantially different between the two generations and body styles. The 1970 Chevelle uses a much wider and longer rear end housing. Even if you could somehow adapt the mounting, the width difference alone would create major handling and potentially safety issues.