This is a version of the original MacPro G5 rear fan bracket modified to fit with The Laser Hive's “mATX Original" case conversion kit.
Link to the G5 case conversion kit: https://thelaserhive.com/product/matx-original-kit/
Just in case you don't want to cut up the original part or don't have one.
Similar to the original model, I recommend printing it standing upright to increase the rigidity of the little clip pieces.
The author remixed this model.
Adjusted the model to reflect the modifications needed for The Laser Hive's “mATX Original" Conversion Kit.