The 1984 Hurst/Olds and 1985–87 4-4-2 were equipped with an 8.5" GM corporate differential and all were equipped with 3.73:1 ring and pinion final drive gears. Rather than using the weaker 7.5" rear differential found in the Monte Carlo SS, these models used the same stout unit found in the Buick Grand National. Many 4-4-2s (and G-body Hurst/Olds) did not come with RPO G80 (limited-slip). This was, in large part, due to dealer ordering "packages" that grouped popular options together for ease of ordering. Problem was, G80 was not part of a single one of those popular option packages, but could be added "a la carte." For the most part, performance-savvy dealers and customers were the only ones opting for the limited-slip.