Longer shocks are needed when you need longer shocks. IF you go from completely stock to a shackle, then you are probably ok... but you lose however much lift you got in suspension droop. If you have lift blocks and add a leaf and shackles, you will probably need new shocks. On the other hand, if you lift it 4", you might not be able to go get shocks that are 4" longer because you may bottom them out when the suspension is compressed.

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