Hello from a newly converted bowtie fan.
Disk brakes were a factory option, if it is factory, it will have the small bolt pattern wheels
There are disk conversions which retain the small pattern, "Scarebird" is one
If you have big bolt pattern wheels (4.5" or same as Ford/ B body Mopar) then someone has put 73/ later Mopar spindles/ brakes on
You need to find out in case you need parts. Find out how many pistons are in the caliper One big single piston is the 73/ later brakes.