I have a suspect riser on one engine. I have no problem replacing them with new ones but my concern is getting the to match up right with the transom tips. The risers are long dry type that end about an inch from the tip. they are mounted to EMI manifolds but the risers don't look like EMI's Will post a couple pictures when I get the off the boat.

If your engine is in the correct Mercruiser position, EMI risers will fit. You can get the measuring dimensions from their webpage here http://eddiemarine.com/image/data/EM...Dimensions.pdf

Also, they are very helpful with issues like you are having. If you are concerned about the riser's dimensions you could send them in. Their customer service treated me perfectly when I needed a hand.