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In 2002 Mercruiser changed on the V6 and Small Block V8 engines from the standard style of exhaust to the newer Dry Joint Exhaust systems. The purpose of this was to reduce the risk of leakage at the gasket between the manifold and exhaust riser. It should also be noted that the height and down angle of the exhaust elbow changed as well. It was felt that the overall height of the exhaust elbow should be raised to meet the total height of the engine. Therefore Mercruiser created the 1.5" taller exhaust elbow which included a 14 degree down angle versus the standard 7 degree. This then created an issue regarding the use of risers. For example when 3" risers/spacers are installed along with the taller elbow this means the overall height of that installation was taller than the previous installation with 3" risers. Therefore Mercruiser created the 1.7" and 4.5" riser/spacer to account for these installations where the standard 3" & 6" spacers were already at a package height limit.

Short Dry Joint Elbow p/n 864309T02 s/n 309999 and below (pre 2005 models) - Measures 5.2 from elbow flange to mounting bolt bass pad. SELECT THIS LINK TO VIEW EXHAUST DRAWING.

Tall Dry Joint Elbow p/n 864591T02 s/n 310000 and above (post 2005 models) - Measures 6.7 from elbow flange to mounting bolt bass pad. SELECT THIS LINK TO VIEW EXHAUST DRAWING.

If you are trying to replace an older NON DRY JOINT exhaust with the improved DRY JOINT system this is possible, however you will most likely need to use the "Short" Dry-Joint elbow/riser as this will be the closest fit to the old Non-Dry Joint Elbow/Riser being replaced. The p/n for the needed restrictor style dry-joint gasket is 27-864850A02 (select link).

Mercruiser also had 2 different Dry Joint Exhaust Systems available on the 8.1L (496 CID) engines. Select these links to view the differences and associated systems.

Link to ........ V6 Standard Exhaust (serial number 0M614999 and below)
Link to ........ V6 Dry Joint Exhaust (serial number 0M615000 and up)

Link to ........ V8 Standard Exhaust (serial number 0M299999 and below)
Link to ........ V8 Dry Joint Exhaust (serial number 0M300000 and up)

Link to ........Stainless Riser Exhaust System
Link to.........Cast Iron Riser Exhaust System

Link to ........ 8.1L Exhaust with Water Rail
Link to ........ 8.1L Exhaust with W/O Rail