There were design studies for the 767-100 and 777-100.
The 761 was a shortened 762, intended to serve the same payload capability as the 752. The 752 was much more efficient so the 761 was dropped.
The 771 was intended to serve the same markets as the 772LR such as SIN
. It was envisoned to use the same MTOW's and engines as the 772ER so the only way the missions could be flown was with a shortened body and fewer passengers. As a result, the economics were not good so the idea was dropped.