Congratulations, thurman

That truck looks real nice.

It looks like you have done your homework on being ready for the NC DMV.

Do you have a Shop Manual?
That will have an illustration of of the ID plate location and code.
available on eBay for about $27

That will allow you to "educate" the DMV big-truck/antique registration agent, if necessary.
My agent was real interested in seeing the GM ID documentation from the Specifications Manual (that you have) and from the Shop Manual).

Please PM me (and give me your phone number), if you want to discuss my pleasant dealings with my NC DMV big-truck/antique registration agent.

Good luck, and, let us know how you registration works out.