intake/exhaust manifolds

I am not very knowledgable about Allis Chalmers even thought I spent my childhood mowing grass with an IB and bush hog in the Florida swamps.  In my later years I have acquired an B and An IB.  The B has an annoying leak behind the manifold so I thought I would take it off and see what was going on.  When I went to purchase a gasket, I discovered that the manifold on my B is not the same as the one in the catalogs for a B.  Mine looks more like the one for a WD45, I guess my question would be "are the two manifolds interchangeable or do I have a strange mixture of parts here? "  My first look seems to show all the ports lining up satisfactorily but I am still in the cleaning stage and I don't have a gasket yet so I cannot be 100 percent sure.  The tractor ran good for a couple of years but after being trapped in a hurricane wrecked barn it seems to have developed a few small problems.  I would appreciate any info anyone could give me about this.  Thanks,

Thanks for the reply,  I was fortunate enough to find an old AC man living close by and he came over and got me straightened out on the manifolds.  Sadly, it turned out I had to buy a new one and like all old tractor stuff, it was expensive.  Again, Thank you. It 's nice to know we have this forum and helpful folks like you in it to keep us (and the old iron) going.

I'm always happy I can still buy a new part,forget the price!