Just measured 4 guns, all blued :
1973 Service Six (low back) 0.1240 Width 0.0937 Depth
1974 Speed Six (low back) 0.1235 Width 0.0937 Depth
1976 Speed Six (high back) 0.1450 Width 0.0781 Depth
1983 Service Six (high back) 0.1420 Width 0.0781 Depth
CAVEAT: these were just 4 picked randomly from my collection