Gimbal Housing Part Numbers

[76SeaRay]

After a lot of research on gimbal housing castings, here is a chart that I have created using the info I found. I believe that to convert from 4 bolt offset Y pipe bolt pattern to the 5 bolt pattern compatible with newer Y pipes with non-offset bolts, the 42559-C casting was created by Mercruiser in the transition period (89 to 91) of Alpha One Gen One to Alpha One Gen Two to satisfy old and new Y pipes. Looking for comments and feedback on this chart. I will update it with corrected or additional information if anyone has more info.

 

[76SeaRay]

As a follow up, I received a very nice used gimbal housing casting number 42259-C with the 5 hole exhaust mount. I have checked it as closely as I can against my original 42259 (with no suffix) and it appears that the only difference is the additional bolt hole at the top for the 5 bolt pattern of the 42259-C. I haven't installed it yet but it would appear that this allows the 4 inch exhaust Y pipe that I need to use to replace my old 3 inch Y pipe. So, it appears to me that the 42259-C is backward compatible on the Alpha Gen One with the 3 inch Y pipe. I can't say that the 42259-C will work on a Gen Two. The 42259-C case is narrower at the steering arm and does not have the gear oil pass through tube of the Gen Two. So, in the chart I provided, I would remove the Gen Two for the 42259-C at this point.