traction and load handling problems

[rcachevy]

hi guys,i'm new here and i've got some questions for you.first off my truck is a 67 lwb i have 3 in drop springs in the back and i replaced the trailing arm and trac bar bushings w/poly ones i'm running kyb monomax shocks and no sway bar.with decent tires i've always kind of had traction problems and i don't have much horsepower and recently when it has a little bit of a load in the bed it sags and acts squirrely,but the springs are only about 3 yrs old.so before i try to drill through the frame to run air lines for the old style air bags that go inside the coil spring does anybody have a better suggestion ? also i need new lower shock mounts suggestions on where i should buy them ?and finally has anbody else had trouble with the 10% ethaanol mixed with our gasoline eating up the plastic blazer gas tanks ? if so does anybody know where you can buy the good old fashioned galvenized metal ones cheep ? sorry for being long winded but trust me i've got many more questions these are the most pressing,Ron