M38A1 CDN2 Under-hood Markings
 

Noted some red paint showing through and uncovered these markings forward of the radiator - can anyone tell me what they mean?

If the picture isn't clear, it appears to say "A/F/72".

In the fall the mechanics would run around the compound doing a check of the antifreeze strength before winter. Although A/F strength was a operators job, it was still a worthwhile investment of a couple of the mechanics time, since it was quicker to check the whole lot than to have to replace engines for cracked blocks. Once the AF was checked, and strengthened to -50 if required, a stencil would be applied, sometimes under the hood, sometimes on the outside of the vehicle.

Yours was apparently checked in such a situation back in 1972.