Optic mounts for P Series Pistols

[RDLSAT]

I have been searching for a Rear Sight Dovetail Optic Mount for a Ruger P89DC. Specifically with the Holosun K footprint.
I have come across many vendors that say they have mounts that will fit P85/95/97, & MK Series pistols. But they also say these same mounts will not fit the P89.
Can anyone tell me why this might be? Is the dovetail groove cut differently on the P89 than all other P Series pistols?
Has anyone out there found a mount that fits the P89?

[contender]

I'm not sure,, but I think the P85 & the P89 have the same dovetail cut.

Worst case,, if you get a P85 mount,, and the dovetail is a little different,, then have a gunsmith mill the mount to fit the P89.