I am in the middle of an axle swap on my 1983 K5 (former 6.2 diesel). The donor vehicle is a 1979 Suburban with rear corp 14 bolt. MY QUESTIONs are ... does a 3/4 ton have a different spring pack with different weight stuff? I will be pulling a travel trailer and would like that advantage. . In appearance, the two springs appear to be the same, the donor suburban spring seems to have a large second overload or thicker spring on the bottom than the K5 stock springs. The K5 spring pack is 2-1/2" and the Sub is 3" thick (go figure). Second question, will the 3/4 springs need a different size lift block? I have a 4" rancho spring lift from the suburban on front? I unfortunately cannot afford rear springs at this point and I have several different blocks to choose from.... Thanks in advance for your help...... rezaB Built for a purpose.