Yeah the Blazer with the 39.5" Swampers looks like it has 4" lift springs, extended front shackles and a 1/2" thick plate between the spring and spring perch. This in additon to the higher spring perch of the Dana 60 is more like 6" of lift on a 1/2 ton axle equipped K5. This and the sawzall is plenty of room for 39.5" Swampers.
CB
1973 K5, 400TPI,TH350, 203/205, Dana60/Detroit/5.38 front and rear, 4" lift, 38" TSL's on steel wheels