Low Ratio Carrier (3.73 & Down):Fits gear ratios like 3.07, 3.54, 3.73
High Ratio Carrier (3.92 & Up):Fits gear ratios like 3.92, 4.11, 4.56, 4.88, 5.13
If upgrading from low gears to higher, a new "4-series" carrier or a thick-gears set is required.
It really depends on what ARB you bought. I...