Perhaps the most important consideration when building a mild 8-inch axle is the casting itself. If you have a '65 or '66 Mustang, then your axle uses the single-web casting similar to the one shown at the left. While adequate for normal use, you can see that this piece won't be nearly as strong as the '67 and later casting shown at the right. The extra webbing strengthens the casting substantially, and it is the piece you want if you're interested in a more stout 8-inch axle. Since our car is a '68 model, it already came with the improved casting. After the '66 model year, the single web casting was relegated to six-cylinder use only.