2 questions 88-90 suburban 3/4 4X4

[jonzcustomshop]

I am putting the running gear off a wrecked 89 (I think) 3/4 ton 4X4 suburban on my 64 suburban....
the transfer case has a wire connected to it, it has an oval plug, and 2 connections inside, I have traced the wire as far as the area around the fuse box, there it looks to split in 2 directions , 1 going towards the inst. cluster , and the other into the harness.....
what is this for? do I need it?

there is a lever connected to the top of the rear end housing, it looks to be 3 pieces, and the top piece looks to have the brake line running in, and out of it. there are no electrical connections to this lever.
what is it for? what does it do? and do I need it?


thanks