Overflow bottle
I took one out of a 75 duster slant six, and it bolted right in my factory 73 318 car.
Should not be that hard to find, and it hugs the contour of the fender.
How wide is your radiator, it is a ac radiator need to measure, plenty of room with a non-ac 22" core.
The 72 back never used a factory overflow bottle. If the 73 up will fit you will have to drill a hole for the nub on the bottom to fit in to. If I recall correctly that hole is in the frame rail. If you get a 73 up bottle make sure you get the metal mounting bracket with it.
You will also need to buy a radiator cap that will work with an overflow bottle because the original one won't.
I took one out of a 75 duster slant six, and it bolted right in my factory 73 318 car.
Should not be that hard to find, and it hugs the contour of the fender.
How wide is your radiator, it is a ac radiator need to measure, plenty of room with a non-ac 22" core.