I found the same info from the site you did which says,
"In 1985, the following units remained as assigned to the 49th Armored Division: 1/133; 3/133; 4/133. All were 105mm SP units."
There is no question that at one point the 49th had M108s as I found the following in a unit history of the 49th which deals with the period surrounding the Berlin Wall crisis:
"Armored Field Artillery units were being supplied with modern weapons including the M-108 self propelled gun (sic), replacing World War II era M-7 self-propelled 105 mm. guns."
(Sorry boys, it's a HOWITZER not a gun!)
But this was in 1961.
Anything is POSSIBLE especially when dealing with the National Guard, but while it's certainly true that the Guard often had much older equipment, it's difficult to imagine that even the Guard still had M108s in 1985.
I'm thinking the 1985 may be a typo, but it's certainly correct for the early 60's.
As far as the unit markings go, that's a mystery. The "2F28" portion would tend to indicate 2nd Bn, 28th Field Artillery. The "11" in front is the problem. (There is no 12th Bn or 112th Bn of the 28th FA).
Another problem is that 2/28 FA went from M107 (175mm Gun) to M109A2s sometime between 1969 and 1983. And they were part of 210th FA Group, which supported VII Corps. I found a picture of a vehicle from another BN in the group which indicates that the unit ID should read "7A2F28".
Perhaps Italeri didn't do such a good job of research.
I'm thinking an all OD M108 with "49 ^ 1F133" might be correct for that time frame.