Do not use any type of grease between the leafs as it attracts dirt and will cause the springs to actually become stiffer.
The old model A's did use grease and were wrapped in a burlap type material but these are really a mess to deal with.
Best is to bevel the ends of each leaf with a grinder so as not to allow the leading edge of that leaf to dig into the adjacent leaf. That's really all that is necessary. Then assemble and paint the entire spring pack as a unit.
You can use the poly spring liner between leafs but in trucks it sometimes makes the suspension too soft.
OK I'll leaf off on this discussion here............... :-)

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