This unit is doubled drilled for both 7/16in./½ ring gear bolts. Must use YSPBLT-027 to work with 3/8in. ring gear bolts. Yukon recommends the use of high grade Non-Synthetic GL-5 gear oil and Yukon LSD (Limited Slip Differential) additive for long life and smooth operation. Part number OILADD. The use of synthetic oil is not recommended and may result in aggressive or noisy operation.