Finding my late dad's other truck - 1972 K20 4x4 LWB

[InNeedofaDelorean]

Hello everyone, I've decided to attempt to hunt down my father's other old truck. If any of you remember, I posted on the board trying to hunt down his 1968 GMC 4x4 SWB - which I did find, but they refused to sell it.

Long story short, my dad (username here, jeffspower http://67-72chevytrucks.com/vboard/member.php?u=7598) passed away 2 and a half years ago - and these trucks was his thing, and as such, my thing. The 72 is what I learned to drive in, and it was powered by a 500 CI engine from an El Dorado that my mom wrapped around a telephone pole. I grew up with this truck, learned some skills thanks to this truck, and had a ton of great memories with it.

It was sold May 5th, 2010 to I believe some classic car dealer in Omaha. It for sure went to somewhere in Omaha, after that we never kept track of it.

I have very little info on it- all I know is what I got from my dad's sig on this site "'72 K20 500 Cad/TH400/NP205"- all the paperwork was thrown away over 7 years ago. All I got is what I know it had when we had it - a 500 CI engine from a Cadillac, 4x4, mismatched vector-style rims, bondo in the bed on the passenger side rear (and a few more areas if I remember right), right behind the tires, and a grey interior with newer seats. I remember telling him that the grey clashed with the red big time, but he didn't give a ****, haha. It also had a modern radio in it.
EDIT: some info I found from my dad's super old posts. This is all info from 2008, so it may be REALLY out of date now that it's been 7 years since we sold it.
-It has power seats out of a '99 Silverado
-It has a gas tank from a blazer

Would it be possible to call up the relevant authorities and see if it's listed on old tax papers of his? Is that even possible?

Now for pictures - most of them are crowding 10 years old. One of which is a shot we took of the guy leaving with the truck - only able to get the phone number on the trailer, 402-201-57, ending with either 69, 63, or 68, I can't tell.