Trying to figure out my brakes

1972 was the final year of the great-in-theory-but-failure-prone-in-application Kelsey-Hayes 4 piston calipre disc brakes .

As mentioned , these could be had with or without vacuum assist ; 340 Swingers had the disc brakes sans booster as standard fare .
Look for codes "B41" ( disc brakes ) and "B51" ( power boosted disc brakes ) on your car's fender tag and/or build sheet .

My first car was a 1972 Swinger , and it had the power disc brakes ( 318 / 904 combo driver train ) .
I constantly had problems with those brakes !!!
The pistons would come-out unevenly , thereby causing a pulsating brake pedal and premature pad wear .
Naturally , the rear drums would overcompensate for the lack of braking power on the front , and would lock-up easily ( ever try to find those odd ball 10x1.75" drums ? Expensive as hell ; these actually had a core charge on them !! Guess they'd reline them with a new friction surface ) .

If you wish to keep those factory brakes ( e.g. , if your car's a resto ) , do yourself a solid and have the calipres rebilt with stainless piston sleeves , and use D.O.T. 5 silicone brake fluid ONLY .
I did that temporarily on my '72 until I was able to convert the car to the superior '73 & up setup .

Parts are much easier to find for these brakes these days ; but back when I had my '72
( 20 + years ago !! ) , parts were nearly impossible to find !!