Long story short I am working on my son's 5.0 MPI SN 0m6011815 for a water leak at #1. I found a pinhole rust leak upper end of intake tract behind the T-stat housing. This SN engine calls for MANIFOLD Intake #1 PN 8M0083536 (also 8M0104793) and is not available anywhere we can find.
https://www.mercruiserparts.com/bam/.../31849/8093/90

Older SN ranges of the 5.0 MPI call for Manifold Intake, Lower #1 PN 8M0097032 (not in my SN range, older)
https://www.mercruiserparts.com/bam/...31859/15323/90

I did find one website that may incorrectly call out that the 8M0097032 is the Superceeded part for the 8M0083536
https://marineengines4less.com/mercr...art-8m0097032/

I checked the Upper Intake and Fuel Rail PN on the above two BAM links and they are the same. This tells me it will bolt up to the heads and the existing Upper Manifold. The Injector PN differs. on BAM website but not on Mercury PN catalog between any of the SN ranges and in addition to that it calls out the older SN range of the intake the same on all SN ranges. which differs from BAM
EzPartsWeb (sysonline.com)

WTF, I know things can't be updated perfectly so the real question becomes if the bore size for the injector is the same on lower intake 8M0083536 and 8M0097032 and or if the injector dimensions where it inserts into the bore of the lower intake the same
879312003 at BAM on first link vs the injector 885176 at second BAM link

This is hard to follow and there may be some bad info on sites but I cannot find anyone who seems to know what specifically the difference is between the 8m0083536 and 8m0097032. To further confuse the situation see the magnifying glass on both to the line 1 parts and read the supeceeded, seems one leads to the other then the other with only a 001 difference. Arghhh

so looking at the 2 different injectors, I do NOT see a sealing size difference, they both appear to be what id call a 14 mm/ 14.5 mm bottom end fwiw,

Ok, Articfriends and I have been chasing this down, his part of the project was simply to clean/test my injectors and he stepped up to assist in the Intake Lower parts issue and injector fitment between the two Lower intakes. To sum up, the newer PN Intake that I have and is rusted away is NLA. The older PN 8M0097032 is scarce but I may have located one that is reported (not yet confirmed) a different bore diameter (not sure if first bore or second bore) where the Injector sits.

We believe that the REPORTED bore size being different is incorrect and simply the Injector ID where O-ring sits is larger. Possibly, the last stepped hole is different but that should not be an issue as the diameter of the sealing surface may be the same. Both manifolds use the same Upper intake as well as fuel rails etc. The only difference I see is the Injector PN and O-ring kit. One Injector is 24 and the other 27lbs. Pictures (from one source) indicate that the injector tip is larger on the 97032 Intake mating injector but is unknown for the actual O-ring sizes OD is different between the two Injectors.

Clear as mud yet? I need a beer. The pic shows there are 3 dimensions involved, the tapered area, first bore where the injector seals and the bore exposed to the intake tract/runner. I have ordered the older 97032 intake and will update my findings.

In the end, the register where injector seals will be 14 14.5 mm on both (from everything I know)