I have a few projects and i am hooked on my new LS3’s. I do have a horror story i commissioned a car builder to built my dad who passed’s 1960 Chevy pick up. High budget , i wanted to make this thing really nice Boosted Bertha nice. Well after $74k and months behind schedule and the work suspect at best i am still $74 k away from finishing. But thats not why i am here. I did take my truck and parts back. The problem i have is the guy faked my motor paperwork from LKQ he literally photo shopped a 2013 invoice and LKQ said he hasn’t bought nothing in 6 years! It’s not a Ls3 and 4l80 its a L99 and 6l80 but thats all i know. Suppose to have 13000 miles on it but really who knows now. I have heard it may even be stolen. Where do i find the serial number? I dont want to build this thing up to 650 plus hp with a ton of chrome only to find out its stolen and dude gets his motor back dialed in. Can anyone help me locate this number so i can check NICB for motor?

L99 need to know where serial number is

Welcome to LS1Tech! Sorry to hear about your misfortunes. I’m on several automotive forums myself, and it always hurts to hear of shops doing this kind of stuff, and unfortunately it’s more often than you’d think.
Re-post this question over in the Gen4 External section. You’ll get way more traffic over there, and someone will have an answer for you.