This was bugging me a bit. The inscription says "FMHUSKYCHARLIE" which means (fairly) clearly "From Husky Charlie," but who is "Husky Charlie?" At first I thought it maybe was a joking reference to the enemy, but the Viet Cong were known as VC, "Victor Charlie", not "Husky Charlie."
A little more searching turned up another lessons learned report at DTIC, which has the answer:
The unit in question was Battery C, 2nd Battalion, 35th Artillery, an artillery battery in the battalion that was commanded by LTC Gendron. That unit had the tracked M109 Self-Propelled Howitzers with the 155mm cannon mounted on it. I'm guessing that "Husky" referred to Howitzer(s), and the Charlie was of course for the C in Battery C.
At the time of this particular report LTC Gendron had moved on and another commander was in place, and they arty guys were involved in turning back the Tet Offensive.
https://apps.dtic.mil/dtic/tr/fulltext/u2/391449.pdf
Nice detective work!