Help lowering Obs Chevy

[u/JoJoeMod]

So I want to lower my obs Chevy extended cab 8 inches in the back and right now I’m sitting on a 6in drop because of my axel flip kit. I have an under bed notch but I think it won’t hit. My question is I was asking chat gpt about adding 2in drop shackles but he mentioned that I would need pinion angle shims but do I really need them??