Chevrolet and GMC models of the 2007 to 2013/14 GMT900 truck line apparently use their accurate platform code in the IMCDb:
• Chevrolet Silverado: GMT901
• GMC Sierra: GMT902
• Chevrolet Tahoe: GMT921
• GMC Yukon: GMT922
• Chevrolet Suburban: GMT931
• GMC Yukon XL: GMT932
• Chevrolet Avalanche : GMT941

Shouldn't the Cadillac equivalent models be handled the same way?
• Escalade (for now GMT920, should be GMT926)
• Escalade ESV (GMT930, should be GMT936)
• Escalade EXT (GMT940, should be GMT946)

This way, the generic GMT920, GMT930 and GMT940 codes could be kept for vehicles whose make is not recognizable.