I have an xbox that is making alot of loud humming noise. I figure it's either the GPU fan, case fan, or CD drive. Before I buy another one for parts, are there any differences in the fans between models? I know there's differences in the CD drive, but as long as it's the same make of drive it's plug and play, correct?

It doesn't need to be the same make of DVD drive at all - on the Xbox 1 all of the DVD drives are interchangeable.

The GPU only has a fan on the version 1.0 Xbox models, so there are no different fan versions. On the later models it's a passive heatsink.

I'm fairly certain that the case fans are identical across all models, and are standard 70mm fans, similar to this one.

Thanks again Heimdall! Now to crack the box back open and see what the noise is from.