"117" in this case stands for January 17, 1968. They used 1-9 for January - September, than they used A - October, B - November, and C- December. Production for the new model year generally started August 1st. So the numbering would indicate as follows:

1- January 1968

2-February 1968

3-March 1968

4-April 1968

5-May 1968

6-June 1968

7-July 1968

8-August 1967

9-September 1967

A- October 1967

B-November 1967

C-December 1967

The 17 is the day indicator, as in the 17th.