First - paint for all these markings. Small model enamels such as Testor's may be difficult for some of these since you may use more than one bottle for some markings but they have a good variety of colors or at least bases you can mix the right colors from by combining. If doing so mix all you can of the color matching color don't want to run short since the second batch will likely not match the first. Since your only doing one car Rustoleum small cans is likely too much paint depending on the cost though if your doing all of the suspension a can of yellow, since there is often more of that than any other color, might be best to go that route.
For the coloring your the best judge since you can see them in person but will give this a shot. Looks like a standard 69 9" rearend and third member
As for the specific marks you posted
1- Third picture and #1 on your list does, in the picture appear to be done in white paint. A similar (different number as well as this) has been found on other examples in one of three of the four (sections at the top of the third member divided by the two largo reinforcement ribs. Either the (as looking at it from the front of the car) the upper left or one of the two sections on the top right corner. Most are found as a two digit number in my records. Have found them in a couple of different color including white
2- The first picture and #2 on your list. Is that on the top of the bottom of the rear housing?
3- Second picture and #3 on your list. There was one worker at the Sterling rearend/axle plant that like to circle the coding located here on the third member. I've first found these popping up during 67 production. Have not found any others from 69's with the circle yet so would have to refer back to that workers efforts from prior years. The challenge is that typically that area has a 3 digit coding that starts with the letter "V". Have found these marked with paint in one of four different colors. Not sure that the color used has any significance
Hope this helps some
