1970 Duster base model slant 6 rear differential 2070051 spider kit

The 7 1/4 is "ok" in its element. It's considered the "6 cyl" or "light duty" rear axle and as long as it's used in those applications, it's sufficient. It's when the rear axle is either neglected or used out of its element that it fails. Millions of Chrysler products came with them.