RE: LST serial number significance
my guesses:
side rails ~#3000
clutch springs ~#5000
CVD's ~#6000
washer - ~#11000 (USA) or #9000 (UK)
my truck #3350 had new side rails, but old clutch springs and CVD's, and an engine with a washer. mine is a UK truck and did not come with all the updates.