I can tell you a lot about this genset. What is it you want to know?
Cat/Olympian was originally a joint venture with Generac I believe.
The tags and pictures you show are Generac through and through. Generac is not known for supporting stuff this old, Cat is, but I don't know how much of this ever filtered into the Cat system.
After a while, Cat and Generac did not get along and production of Olympian moved to FG Wilson and I have had very good success with ordering parts for those but they are a whole different animal, only similarity is the name and that they are yellow.
That engine is a Mazda or possibly some other clone.
If it is a 3.0L engine then it is most likely a Mazda HA engine, looks identical to me. According to this
https://en.wikipedia.org/wiki/Mazda_Diesel_engine it was licensed from Perkins who never built any.
I don't know if it was ever used in anything but Generac in the US. Generac has a habit of using special engines that nobody else uses. Once support dries up it can be hard.
The 94 in the number indicates 1994. Contact a Generac industrial dealer that is large and experienced would be your best hope.