It looks like I have a Crankcase vent on middle iron below filler neck on my FD? I thought only the FC had this.

 

As I mentioned, yes it is crankcase. It's just a hold over on the FD housings from the FC and not all FD intermediate housings have them. It's never used on the FD and motors from Mazda with them had them capped off. You can either cap it or use it as an extra crankcase vent line.

 

I never doubted you, just figured posting it separate would get a definante as to why I have it but you just answered it for me. I would think it would be beneficial to vent it if I was to do alot of tracking with the car.

 

don't cap it. there's a reason why FC's have less crankcase ventilation problems than FD's. You might as well take advantage of your oddball housing.