There was no D-25-12 in the 70ies...and there was no D-212 in the 70's either. (there was a G-212 but not with mahogany colored top I think).
So the one on the pictures cannot be a 70's guitar at all I'd say.
As Hans wrote (above link), the D-25-12 was introduced 1987, before that it was called D-212. I found a D-212M (for mahogany color) in the 5/1/1986 pricelist but don't know when that model actually was introduced. The (often incorrect) serial number list on the Guild webpage shows the D-212 introduced in 1981. The 1/15/87 pricelist shows the D-25-12 already.
So my guess would be that the one on the picture is a D-212 from the 1981 to 1986 range. Without knowing the serial number it might be hard to limit that date range further.
I hope that Hans can update us on this Tom Petty guitar if he has any more detailed info in the meantime (I mean since his above post from year 2005).
Ralf