What is it mixed with?
 

Maybe a Toyata?
http://detroit.craigslist.org/wyn/pet/1946735883.html
http://img.photobucket.com/albums/v6.../datsunmix.jpg
Brindle coat from a boxer, but the face kinda looks like a Beagle... though the ears a little short... but I see NO Datsun, besides they stopped making them in 1983 and this pup is clearly not that old.