The rearend in my 83 C20 has 4.56 gears. I think 3.73s might work better in this application and allow for better gas mileage. What whould be the best way to go about this? Is there a proper description to call this rearend such as 12bolt truck? It has a different housing than the passenger car and has big brakes. Are 3.73 gears readily available or would possibly finding a complete rear end assy from the boneyard be cheaper?