Many moons ago, I had a 86 Gulfstream with the 460, according to the receipts I found when I bought it(2000)the original owner had replaced 2 passenger side and one drivers side manifold. Right after I got it, it developed an exhaust leak and progressively got louder. I had a friend who worked at a local salvage yard and he told me about an after market manifold that was a lot better than Fords replacement. I bought one and had it installed, it never leaked again and was still fine when I sold the m/h in 2005. Was going to use Thorley's which at that time if I remember correctly were like 300.00 for the pair. Who makes headers for V-10's