Our 454 Crusaders in our 1986 36 Hatteras have 12" risers. It seems that they are very rare and no longer made. Our boat was in fresh water until 2006 so we wern't concerned. After a friends 36' Tiara ruined an engine from a corroded through riser after 5 years in salt water I really got concerned. I could have bolted 8" risers to 4" risers and cobbled the boat to make them work. About $1900 worth of corrodable iron parts was needed. We found a company, (Marine Manifolds), in Farmingdale NY. that makes replacements out of an alloy of copper and nickel. $3200 for all four and we are all set for the life of the boat. They fit great, stay cool, and pass the water through just fine. I highly recommend these guys the next time your risers and elbows are due for replacement. Just send them one of your old risers and elbows and they will make the copper/nickel replacements. Great folks for sure.
