'73-'76 A bodies had them.
They looked similar, but there were 2 different versions. The '73 had 2 rubber lines from the cap, 1 to the radiator, and a discharge line clipped to the side of the body.
'74-'76 had one line to the tank from the radiator, the overflow was a molded-in part of the body.
The mounting bracket was slightly different between the two, also.
They are interchangeable.
You will also need to use the later radiator cap for the system to function properly.
Some pics I pilfered from other threads:
'73:
'74 and up:
They retrofit just fine onto older cars/radiators as long as the correct radiator cap is used.
The only real mod you have to do on the early cars is drill a hole in the top of the passenger frame rail- 1/2" IIRC. This is to accommodate the small locating "finger" at the bottom of the tank.
View attachment 1716498193
You may or may not need to drill 2 small holes- 3/16" or so- in the upper radiator yoke for the 2 small bracket studs; some cars have them, some do not.
In this pic you can kinda see where I even able to mount one in my '66; the bracket holes were already there (don't know what they would have been for in '66, but they fit the bracket perfectly), I just had to drill the top of the frame rail. The horns got relocated to the driver's side (those holes were already there, too).
View attachment 1716498196
I've put these in my '66 (as mentioned), '68s, and a '70; so I know they fit and work all along the A body production run.