So I'v got a sb400 taken up to a 427ci (still a sb) which i'l be droppin down in the 3rd gen as soon as i buy the car this next weekend. My question is I'v always ran a polyurethane motor mount's and im worried that this engine might be too much for it, whats everyones openion on steel motor mounts ? pro's? con's?

 

I had steel motor mounts on my 69. And although the car isn't built for comfort, the engine shot too many vibrations through the whole car for my liking. I switched to urethane mounts and it did make it better. My mounts are the old style, and they have an interlock built into them sandwiched between the urethane so they can't physically separate. Yours are the clam-shell type which sandwiches the mount by it's own design, and it isn't going anywhere. Trust me, you won't like the steel mounts.