my question is will a exhaust manifold meant for a 12a mount to a 13b? reason I ask is cuz I have found a guy with a divided t4flange exhaust manifold but he says it's for a 12a,and I just need to know if it will mount to a 13b block?

thanks

 

It won't bolt straight on, since the 13B exhuast ports (and hence the manifold studs) are 10mm further apart than 12A ones.