shimano st-6400 hood compatibility

i am chasing some shimano st-6400 hoods, anyone know if st-6510 might be compatible?

I have some 8 and 9 speed 600/ultegra hoods, I’ll compare.

thanks

sorted.

I would say 6500 would not be compatible with 6400.

I’m after some ST-7400 DA hoods too! Bloody rare things