Manifold bodega

Manifold Bodge! Alright all. I have acquired an old 178discovery1 with 208k on the clock. My plan is to keep it alive! At present my problem is that only under acceleration there is a serious rattling that makes the v8 sound like a spitfire plane. I think it maybe the left exhaust manifold. The manifold around the ports are covered in a white cakey paint which I wonder if the PO put on to disguise the problem any insight and thoughts very appreciated. I have done a complete oil change btw to no effect. Cheers all jonathan

The gasket between the manifold and the Y pipe can fail, all you can do is dismantle and reseal using a new gasket or gasket paste or both, but it's not the easiest of jobs.