i got this advice from BUFF (ben) off MSN. i thought everyone could benefit from the advice if they dont know anytihng about BLOCKS and can be used for documentation later for when pepole serach for the advice
Jack up the ute and support with stands under the chassis so the suspension is sagging down at full travel - ok
Have a trolley jack just resting under your diff center just for some added support to stop it moving - even just a jack of some description - its not really holding any weight just gives you a bit of play to jiggle things around in the next step
Spray some WD40 or something on your U-Bolts for your spring hangers on both sides
A trolley jack would be really good if you can borrow one though - because now you have to undo your U-bolts
Its just heaps easier to jack up the diff that extra couple of inches to make it easier to fit the lowering blocks in with out jamming your fingers or anything
Clean the bottom of the diff wear the lowering blocks mount to with a wire brush and same with the leaf spring surface
Now the lowering blocks will sit in between the leaf springs and the diff - make sure they locate properly on the dowels
once you are at this stage - get your new (longer U bolts) and sit them over the diff and through the lowering block holes and the bottom shock mount plate (it all makes sense when you are under there you will see what i mean)
Get your NEW nuts and just run them up evenly on both sides until they start to tighten everything together and then just have another look to make sure nothing has moved and everything is nice and square
Fit your bottom shock mount bolts back again - and further tighten the U bolts keeping them even (so the thread showing on each one stays the same) a couple of turns on one then the other etc etc - but don