Fuel Cell & Frame Spacing Question

[Jahloha]

I am planning out my fuel cell location (under bed & Ill be using Fuel Cell Guy).

Gramps (my grandpa) had some coworker custom fab a hitch for his truck back in 70'. The thing is a beast (see pic). I will not be keeping this hitch because I will be putting the fuel cell there.

Anyways, when measuring the space the fuel cell will go, I realized that there was almost 1.5" in spacing difference (see picture).

So my question, this isn't normal, right? If not, I assume I will need to alter crooked piece to plumb prior to hanging my fuel cell. Should i keep this piece, his coworkers took a nice size chunk out of it (see picture) and has some rust issues. Not sure if I should keep this or just have someone help me fab up a new section.

Sorry for my lack of terminology, still learning a lot as I go.

Thanks everyone!

PS. I will be utilizing a hidden hitch if that matters at all.

Thanks everyone!