Physically GBE and Sawtooth boards are(from any of my side-by side observations) pretty much identical in shape and size. they do use a slightly different PSU pinout though (IIRC GBE is the same as DA PSU and QS is different than DA)

Some of the other things of the board are slightly different like the gigabit ethernet on one and the internal firewire on the sawtooth, but they both have pads for eachother's stuff.