[Shop-talk] Axle ratio?

[Dave Cavanaugh]

I have a 2004 GMC Sierra extended cab, short bed.  I would like to find 
the axle ratio and engine size.  I am pretty sure the engine is a 5.3 
Vortec, but I'm having trouble finding the axle ratio. None of the codes 
in the glove box match anything I read on line.  Any pointers?  I will 
need to be towing a trailer quite a bit in the future and need to know 
how heavy I can go.

Thanks