2002 Silverado 1500 4x4 catalytic converter & pipe
 

I'm trying to replace both catalytic converters on my 2002 Silverado 1500 4x4. I bought a direct fit assembly that is supposed to bolt on to the manifold side (two places) and the muffler side. Problem is, the pieces didn't fit right -- the pipe from the driver's side converter hit the front driveshaft when trying to install, so I took it back. I can't find anything online about having different parts for this for a 2wd versus 4wd. The part I had was a Bosal. The Walker and Magnaflow parts look almost exactly the same, but it is hard to tell the angles of the pipes, etc. from looking at a photo.

Has anyone done this replacement on a 4x4 like mine and can tell me what brand/model they used? I don't want to keep ordering $400+ parts and returning them because they don't fit. Thanks.