Never had rallye mirrors but a body mirrors mount downward. These are side. B or E? No idea. never paid any attention to the mirrors on B bodies. I think that E and A are the same. Also not sure. Either way. What does this belong to?
As much as I hate the cowl hoods they unbolt and can be easily swapped out. So it isnt the end of the world.
BUT, if you have a cowl hood you should probably paint the engine compartment black to complete the chevy look.J/K
if it is only slightly off you can file away at the OD of the marker light. later cars are all just plastic. earlier are metal but doable. just seal prime and paint the inside if it is a metal housing.
take the old quarters, make a pencil rubbing of the original holes. cut the shape out if the pencil rubbing. place it on the new quarters, cut/grind until its properly sized.
Thats what I did on mine and mine had a vinly top and nastiness. Taked care of the encapsulation. They just make sure to put more sealer in to replace what you dug out.