I was looking at putting in a Dual XHD7714 in. Crutchfield says:
Modified Fit - Requires Modification
Installation Details for your 1997 Blazer
» To install this product, you'll have to modify your vehicle. » Extension kit -- when installed, the radio will protrude from the dash by 1-1/2". » Unbolt or cut out the factory stereo's rear support bracket to make room for your new receiver.