The poor quality if the pic makes it hard to say for sure, but here are my thoughts on it. It's a early to mid 70's unit that would likely fit in your II, but may not have been originally intalled in one, nor be one manufactured for Ford by Motorola or Philco who were the original suppliers.
Early '74 units were manufactured by Philco, and would have that name printed on the face of the lens. Not certain, but later units ('75 and up) made by Motorola may have either (Ford), '77 with (Aeronutronic Ford) on the lens, or bear no name like the one in the picture. I have seen units made by other manufacturers such as Bowman industries, that look identical to the Ford units, but do not have the Ford logo embossed into the metal casing of the unit or any name on the lens.
The factory picture I have of a 1974 AM radio does not show any chrome trim around the push buttons....and I don't have pics of later units at hand. So, from that I would conclude that your radio is (possibly) either a 75+ unit for a II, or one that came out of another Ford model altogether. But, I do think that in any case, it would fit into your dash opening.
Without a sticker or permanent ink marking on the unit, it's hard to determine the exact year of manufacture. But, I'm not certain if units made prior to '74 used that particular black camera case type finish. It seems to me the earlier '70's Ford cars used a different style face plate. Hope this helps?
Blue Thunder: II's were available in 1974 with the following radio options:
AM, AM/FM mono, AM/FM stereo, AM/FM stereo w/tape player (8track).