I had a 7 1/4 rear axle with 4" wbp,open dff,in a 170 cu in - /6 68 Dart with stock 13" rims with a 1.76 gear

only ones I ever seen

dint last long with the 318 though!shure would fly on the open road too,just didnt stop with 9" drums all the way around

try dr diff or randy r&p