I decided to list the last airdate of each pre-79 week. If anyone has any corrections or can fill in any of the unknowns, let me know:
1-5: Unknown, but possibly may not have reran after its first airing (Feb. 19-23, 1968)
6-10: May 12-16, 1969
11-15: May 19-23, 1969
16-20: May 4-8, 1970
21-25: May 11-15, 1970
26-30: May 18-22, 1970
31-35: Unknown, either June 16-20, 1969; or May 25-29, 1970
36-40: Unknown, either June 23-27, 1969; or May 25-29, 1970
41-45: Unknown, either June 30 - July 4, 1969; or May 25-29, 1970
46-50: June 1-5, 1970
51-55: July 14-18, 1969
56-60: June 8-12, 1970
61-65: July 28 - Aug. 1, 1969
66-70: Aug. 4-8, 1969
71-75: Aug. 11-15, 1969
76-80: Aug. 18-22, 1969
81-85: June 15-19, 1970
86-90: June 22-26, 1970
91-95: June 29 - July 3, 1970
96-100: July 6-10, 1970
101-105: July 13-17, 1970
106-110: July 20-24, 1970
111-115: July 27-31, 1970
116-120: Oct. 13-17, 1969
121-125: Aug. 3-7, 1970
126-130: Aug. 10-14, 1970
1001-1020: Dec. 5-30, 1983
1021-1025: Jan. 2-6, 1984
1026-1030: Jan. 9-13, 1984
1031-1035: Unknown, probably Nov. 2-6, 1981
1036-1040: Unknown, probably Oct. 29 - Nov. 2, 1979
1041-1045: Unknown, probably Nov. 9-13, 1981
1046-1050: Unknown, probably Nov. 16-20, 1981
1051-1055: Unknown, probably Feb. 25-29, 1980
1056-1060: Unknown, probably Feb. 13-17, 1978
1061-1065: Jan. 16-20, 1984
1066-1070: June 19-23, 1989
1071-1075: Unknown, probably Dec. 10-14, 1979
1076-1130: June 26 - Sept. 8, 1989
1131-1140: Sept. 11-22, 1989
1141-1195: April 23 - July 6, 1990
1196-1210: July 9 - 27, 1990
1211-1260: April 22 - June 28, 1991
1261-1290: July 1 - Aug. 9, 1991
1291-1295: April 18-22, 1988
1296-1315: Sept. 28 - Oct. 23, 1987
1316-1320: April 25-29, 1988
1321-1325: May 9-13, 1988
1326-1350: May 16 - June 17, 1988
1351-1360: May 11-22, 1992
1361-1365: May 31 - June 4, 1993
1366-1385: May 25 - June 26, 1992
1386-1390: Aug. 7-11, 1995
1391-1395: June 14-18, 1993
1396-1400: Aug. 29 - Sept. 2, 1988
1401-1410: June 21 - July 2, 1993
1411-1420: Sept. 19-30, 1988
1421-1425: July 18-22, 1994
1426-1430: July 12-16, 1993
1431-1435: July 11-15, 1994
1436-1440: July 25-29, 1994
1441-1445: Oct. 10-14, 1988
1446-1455: Aug. 1-12, 1994
1456-1460: June 12-16, 1989