Coincidentally , one of my best friends owned a 66 SS Chevelle factory solid-lifter 4spd car right after high school in early 80's.
In the mid 80's it was stolen from inside his father's Texaco station - while he and his fiance' were vacationing in Myrtle Beach. The day it was stolen, was also his 21st Birthday.
5 years later it was recovered less than 5 miles away.
The person who was harboring the car inside one of his barns for the thief - got pissed with anxiety attacks etc after it still being there for so long ... and called it in.
There were several other dismantled and various stage Chevelles there too.
My friends car was originally a Bronze color with Bronze color interior. Sharp Car
It was now black primer and the interior was spray-can dyed black.
Engine & Tranny removed
VIN and Cowl Tag removed
He recognized and identified his engine & tranny by some certain particulars he recalled when he had rebuilt them. We knew NOTHING about ID codes and ID stamps on engines back then.
Guilford County Sheriff's evidently did not either.
Thief claimed he had sold the engine & tranny - and those in the barn behind my friends car were from a different car.
The sheriff's took the crooks word.
He also claimed the tags were already gone from the car when he took it.
Another insult to injury - and extreme bad judgement - they had dealer license and he always ran dealer tags on the Chevelle. He also left it as open title to avoid property tax on the car (which would have been minimal anyway).
Then above all - he kept the Open Title in the glovebox !!
I had never thought of him as being stupid - but that was stupid.
So Naturally - Title was also Gone
VIN and Cowl Tags Gone
Engine and Tranny Gone
It was a miracle they even let him have the body shell back since he couldn't even provide any VIN proof or proof of ownership history or anything DMV could trace.
He even just slapped inspection stickers on the car when time came due.
No traces.
He couldn't come up with anything showing the VIN .
He bought it from the original owner - but couldn't remember the guys name - and he had moved away.
No one EVER mentioned anything about a VIN being on the frame in those days.
So a Solid Lifter 4spd Chevelle had basically died.
He got a state issued VIN and bonded title - no cowl tag
Fixed her back up fairly nice and kept it a while longer (with a small block)
It took him 3 years to sell the car in the late 90's, for pennies on the dollar.
Terrible story, but felt like sharing it.
Your Brother-In-Law needs to get his shet in proper looking order.
A prospective buyer or even an admirer could recognize what you did and report it.
Then his life and investment goes through he[[
Don't expect your local authorities to be polished professionals in such matters either.
They can bend and twist you any way they see fit once it gets in their hands.