Man CR 900 engine mounts/isolators

Unless rust ate them badly, there should be a small plate on the side of each mount, showing the part #.
It might be hard to see that from a photo, but if the OP can read those plates, it's relatively easy to look for some alternative supplier.
Just be aware that even if the mounts look identical, their part # could be different, due to possibly different hardness of the rubber part between the front and the rear of the engines.
Just for reference, the OEM MAN p/n are "51.96210-70xx", whereas in the "xx" bit (according to their official EU price list) there are 22 different numbers, all with different prices, ranging between 680 and 1800 Euro. I kid you not!

That aside, Breckster, if you don't mind me asking, I'd be interested to hear why you must replace those mounts.
What makes me curious is that my engines (V8/800), even if very different because they were the very last of 100% mechanical MANs, as opposed to yours which were the very first fully electronic CR, are almost identical from the mechanical/dimensions viewpoint. So, I would think your mounts are very similar if not exactly the same as mine.
But if I look at the conditions of mine, I would hope they will outlive me - even if already 22 years old by now!
BTW, pretty sure your engines can't be older, since IIRC the CR900 was introduced in 2005, so it can't be a matter of age...

Wow. A snapped bolt on an engine mount is something I'm glad I never experienced!
In principle, I would agree with the recommendation you got, but it may be worth also investigating further the reason for the failure.

I mean, the best case is a defective part or a bad installation of that particular mount, and the replacement would fix that for good.
But if the bolt snapped due to fatigue, triggered by excessive vibrations, load, or whatever, it might be just a matter of when the new one will snap again...

In your setup, do the engine mounts withstand also the propeller thrust?
In mine, there's a jackshaft connecting the gearbox to a separate V-drive unit, which takes care of transferring the prop/shaft thrust to the hull stringers.
So, what the engine mounts must deal with is only the engine weight and its vibrations while running, but without any additional longitudinal load from prop/shaft.
There's a big difference in engine mounts wear, between the two alternatives...

That is consistent with the coding I previously mentioned.
FWIW, the final "15" makes it a version costing €1700 according to the EU price list.
Though the one I've got is a bit old, and more than likely has been subject to a revision by now...