Yes, it is a direct replacement.
Fram PH3614
The FRAM PH3614 is the oil fiter that cross references with the Onan 122-088 that was installed in the unit. It is half as long as the Onan 122-0800 that is recommended by Onan and actually removed from the engine for replacement. The way the engine cowling is bullt, that means that the oil filter cannot be screwed in or removed because it wsill set too deep in the cavity to get fingers or an oil filter wrench into it.
I did some checking briefly. Did not find a Fram filter for this application.
What is the fram oil filter cross reference for onan oil filter 1220893
Fram CA140
PH 3614
That would be a Fram CA8235
Most cross to a Fram PH 7575
Hyundai,Infiniti, Kia, Mitsubishi, Scion, Subaru, Onan Generators,
Depends on what the equipment you have.
Arzum Onan is 178 cm.
As for as I know Onan never published that information. If it is a non Onan engine. You will have to check with the engine manufacturer.