Will a Silverado classic rear end fit the new body style Silverado?

[hemi43]

I have a new body style 2007 Silverado with 3.42 gears and an open diff. I just picked up a 2003 Silverado for parts, and want to use the rear axle assembly from it because it has 3.73 and locking diff and would help when towing.
I plan on using my current backing plates and drum brakes, but wanted to find out if the rear axle housings were the same as far as width and spring perch location.
Thanks for any reply