When I lived in Mpls I had three survivor Leeds LS6's in the neighborhood. All three had pretty much the same inspection marks on them and were late March early April cars all built within two weeks of each other. Also, a recently found green Leed's LS6 found nearby where I currently live also has similar marks. Unfortunately most all the photos I took were on film and not digital.
You will likely find a "B" pr
"13" on the top side of the cowl just under where the drivers fender bolts to the cowl. Unfortunately I cannot find my photo of this.
Leeds cars all had sprayed undercoating on the firewall above the heater box (photo 1). I usually also see the series number in yellow grease pencil under the black paint somewhere near the vicinity of the one in the photo.
Look in the recessed area of the firewall directly behind the distributor. If you look on a Leeds buildsheet you will see a stamped four digit number in box #1. This is usually found on TOP of the paint in that location also in yellow grease pencil. (photo #2). I also commonly see the two digit paint code written in yellow grease pencil on top of the black paint right behind the booster on Leeds cars. Also look for a yellow line right near where the wire harness clip is behind the booster and also where the cowl relay is attached at the firewall. These were both done to let the line worker know to drill the hole and attach those items there.
As far as the suspension items go, I find these to be fairly common in all plants though no two are ever alike. I find blue, green, orange, pink, and yellow marks on the spindles and usually orange on the steering arm. I have posted many photos of these in the past and you can also read about it here. https://www.chevelles.com/forums/showthread.php?t=397927
The one thing I don't usually see from the other plants is the tie rod sleeve inspection marks but have found them on all the Leeds cars. (See photo #3) Disregard the incorrect 71 and later sway bar brackets as they are incorrect on this car as the 70's did not have holes in them like these shown in the photo. There are two yellow stripes on the center link though I have seen several with white or blue. (photo 4)
Automatic cars have always had part number decals on the coolant lines near the radiator.
M22 cars have a black "WO" stamped on the top of the case (photo 5). Orange overspray on the bellhousing will vary from very slight to full covereage depending on who was painting it at the Tonowanda plant.
There are MANY other details so post questions when you get to them. At the very least, strip the car very carefully especially the suspension and firewall pieces. Use a solvent on the suspension pieces and look for any color markings taking lots of photos to document. On the firewall, lightly wet sand with 400-600 grit paper to bring out any marks only after you carefully washed it. You will find some inspection marks on top of the black paint while others are on bare metal of the firewall. You can check out my threads and my website for many more photos. Hope this helps you.