Out of all the manifolds talked about so far, the Action Plus and the factory 340 are the only two that the Thermoquad can bolt directly to without modification. You see some LD340s every now and then that appear spread bore and people will try to argue they came spread bore, but they did not. The factory 340 (especially the 1971) is a very good piece and if I had one I would not look for an aluminum replacement. I would use it.
