If I recall correctly I thought Marans had white skin. Rocks have yellow skin. The birds pictured appear to be yellow but it can be hard to say for sure in a picture. Look at the bottom of the feet to see for sure.
not all marans have feathered legs but with that being said you have 2 barred rocks.
1. the barring is way to even for the cuckoo pattern which is uneven barring
2. the legs of a cuckoo are supposed to be white not yellow/slate (if they were bcm then they should be slate)
3. at least you have 2 pretty pullets