Tom
The last 3 digits are the date codes. Here's a link to a useful web page for decoding tires.
http://www.barrystiretech.com/dotcoding.html
The decode is:
MD - Tire Co. & plant Goodyear Tire Co. Gadsden, AL
LB - size - E70-14
Y4A - Tire Manufacturer code for the tire
386 - 38th week of 1976, or 1986, or 1996 but not 2006
076 - 7th week of 1976, or 1986, or 1996
441 - 44th week of 1971, or 1981, or 1991