4. We pulled off the calipers, slid the hub/rotor assemblies off, and then removed the six spindle nuts. The’77-’78 Dana 30s have these six-bolt caliper brackets that can be retrofitted to earlier Dana 25 or Dana 27 axles. Score. Later Dana 30s used a two-bolt caliper bracket that attaches to the knuckle and can’t be retrofitted on closed-knuckle axles.