Began in the late 1960s

https://en.wikipedia.org/wiki/KarTrak

"Starting in 1967 all railcar owners were required by the AAR to install ACI labels on their cars. This requirement led to full-scale implementation of the ACI system in the early 1970s. By 1975 90% of all railcars were labeled. The read rate was about 80%, which means that after seven years of service 10% of the labels had failed for reasons such as physical damage and dirt accumulation. The dirt accumulation was most evident on flatcars that had low-mounted labels."

"Unfortunately the maintenance program never gained sufficient compliance. Without maintenance the read rate failed to improve, and the KarTrak system was abandoned by 1977." 

It's pretty rare to see one these days. 

Yes, but...

I understand the ACI label but what are these other ones???

YELLOW DOT

This explains the yellow dot.

http://www.hosam.com/mod/rsdet.html#ui

Art

BLACK BOXES

These are consolidated stencels.

http://www.hosam.com/mod/rsdet.html#con

Art

Date Summary

Links above are good. To comment specifically on the photo features,

ACI (bar code) - applied from 1967-1977

COTS (black boxes) - this style applied from about 1974-1980

U1 (yellow dot on black square) - applied 1978

This placed your photo as 1978-79 at the earliest. If you are modelling the specific year 1970, then all cars should have ACI labels, but none of them should have either of these other decals.

Other Items

Between the two boxes of the consolidated stencil is a yellow warning label stating "keep off roof no running board" indicating the running board was removed.  The B end ladders and brakewheel retain their original configuration, while the A end ladders would have been shortened to four rungs.  There's also a grab mounted to the roof on the B end to replace the one removed with the running board platform.  I can also make out an additional horizontal grab on the A end. above the tack board, and it appears the tack boards have been moved lower (the original position on the door shows as relatively unweathered).

Any of the above could apply to cars shopped after the safety appliance regulations were changed in 1966.  Sometimes tack boards were repositioned before then. 

Thanks!

Thanks for the great information everyone! Now to start decaling...

RE: U1 wheel dots

Remember that ONLY equipment with 33" wheels go the U1 wheel dots.  100-ton cars with 36" wheels (such as covered hopper cars, big coal gons, etc.) did not get them. 

I'm trying to do this also for a 1979-era railroad.  As the U1 dots were applied to all equipment in service with 33" wheels at the time, you would often see a fresh U1 dot applied to a weathered car.  Rip tracks across the country were engaged in this inspection program so there was no standardization about where the U1 dot got applied.  Placement was generally on the lower part of right side of the car. But the specific location could vary quite a bit, even between otherwise identical cars in the same number series.  On boxcars they needed to be where they would not be obscured by an open boxcar door.

- Norm

Not exactly

Norm A. said: "ONLY equipment with 33" wheels go the U1 wheel dots."

That was the plan, and only cars with 33" wheels needed them. But it is not hard to find photos of cars with 36" wheels that got slapped with the stickers in 1978-79.  Better safe than sorry, I guess.

Detailed guide

pulled together some notes and dates from several sources and illustrated in a blog post:

http://vanderheide.ca/blog/2017/09/29/dating-via-the-details/