F-150/250 coil spacers

[Isles4evr]

I have head a lot about people putting f-150 or 250 coil spacers on the rigs for an added 1.5-2" of lift. Is it a good idea? Is it safe? How had are they to install? Which one is better, f-150 or 250? Would I have to get new shocks after the spacers? And last, what type of extended shackles are the best to use to level it out?

Thanks
Chris

Oh yeah, if anyone has the part number because I could not find it, I would appreciate it.