Any links where I can get a 4 HI harness? Tried searching on this forum and "no results" or nothing that applied
LMC Truck and Painless Performance both have options. I haven't used either personally but I've seen other people here recommend them, one earlier in this same thread.
http://www.lmctruck.com/icatalog/cd/full.aspx?Page=64
https://www.painlessperformance.com/wc/lv.php?sl=30817
EDIT - Whoops... Sorry I mis-read your post. LMC has a 4-Hi relay kit in addition to their HD harness offering. @98chevy2500SS said he's using both of them together successfully at the top of page two of this thread. Here's the link to the LMC 4-Hi kit.
http://www.lmctruck.com/icatalog/cd/full.aspx?Page=103