70 chevelle build code ?

[Mr70]

Welcome.
Your trim Tag & VIN# are Typical for Arlington build.
GM's Arlington,Texas plant didn't favor one car model only,as they started producing the 1970 Chevelle-Elco-Monte Carlo after December 1969.
It's quite possible it was delivered to a local Dealer,as
they weren't area specific and were shipped to places like Florida,Ct.,Minn.,Washington,etc.
If you want to look for your Buildsheet,try looking under the carpet,then floor sound deadener first,as this is where I see most Arlingtons BS are found.
Then aim for the Seat backs,Headliner,door panels,etc.

Tell me what color & options you have?
Trans,Rearend ratio,gauges,(Tach redline),Flapper hood,Buckets..
Any pix or cowl tag info to share?