Was able to replace the rear case fan on my Eaton 9130 UPS, and now it runs MUCH quieter, with the air volume rating being close enough to the original part that I'm not worried about it being undercooled, since I'm not using it close to it's max load. (31.4 CFM vs 53.0 CFM).
I did need to put a new terminator on the wire, but once I did that the fan worked fine!