Mercruiser Y pipe confusion

[BEC56]

This past fall I purchased a 1987 Celebrity Bow Rider with a 4.3 mercruiser. Bought it to restore. Upholstery was bad and engine had that "non factory" crack in the side of the block. Boat had spent it's past 14 years inside a barn and had sunken into the dirt floor to the axle. Upon pulling it out with a tractor the tread that had sunken into the dirt came completely off leaving the core of the tires. Oh by the way they actually held air. Love those bias ply Firestones. Floors and stringer are solid. Tap and drilled as advised from this forum. Transom is also dry and solid. Four test drill holes all is well.
Rebuilt all interior panels and finished stitching all the upholstery.
That's the short story and brings me to where I'm at today.
I decided to go ahead and replace the outer gimbal housing seal. Only made sense do to the age of the boat and I already have the engine out. Upon unbolting the Y -Pipe there were only 3 bolt securing it to the gimbal exhaust hosing.
The gimbal housing has the staggered top bolt pattern and the y-pipe does not.
Her we go with assuming!! If I have looked up enough on this forum because of the year the mercruiser out-drive is a Alpha One. The y-pipe is for a Alpha One Gen II.
Checked e-bay the only y-pipe I can find with the staggered top bolt pattern is for 3 in exhaust mine is 4 in.
Looking for knowledge and suggestions.

Attached pics.

Thanks
Bruce

 

[alldodge]

Check the bolt holes, they should line up. The older style only used 3 of the 4 bolt holes.

 

[Bondo]

Ayuh,.... Welcome Aboard,..... The set-up ya got works just fine,....

No reason to change anything, though I'd replace the funky o-ring before puttin' it back together,....

 

[BEC56]

Guys, I thank you for the advise. I figured the 3 bolts that I removed had been there for some time. Just wanted to confirm that with those that have more experience. Assuming that 3 bolts would maintain a tight seal without checking the knowledge available here would only increase my frustration level and give the bilge pump a work out.

Thank you