Where do I find my ECM on a 95 C2500

Engine Control Module a.k.a. my computer needs to be changed. Turns out according to my local dealer that the ECM is keeping my truck from starting. I have the new ECM, I just need to know where the old one is located. I was told it is under the dash on the passenger side, yet there seems to be a lot I can take a part looking for it. Does anyone know a site where there is some pictures or a better way of describing where exactly it is?

Thanks

It was behind the glovebox on my friend's Blazer.