The manifolds took me longer than expected just due to unforseen issues and my clumsiness. As I mentioned I was told to not by new backplates as we could reuse the ones that were on there. Being they were tight to the wall of the engine bay I couldn't see they were cracked or rusted out. Spend the money and buy the new backplates. If your manifolds are in terrible shape then your backplates are just as bad. The clumsiness I speak of is how I kept throwing parts into the river that we needed. That set us back a weekend. Total work time was about 12 hours for both engines.