How to install diff relocating plates

[Bj70v]

Hey I have 2 plates to move the diff at the front forward to clear the back of my guard also castor plates to install to. Anyway just want to check how are these normally installed? Do they go between the diff axle and spring? Also by just looking at it would I need to redrill the ubolt plate? And would the shocks be hitting the sides on that angle? It's on a hzj75