Delta Force, Panama, Operation Just Cause (1989).
Lowe Alpine Tactical Pack (Load Carrying System 1984, LCS-84): The tactical pack is in fact the top lid of the Lowe Alpine LCS-84 backpack. It is easily removed and attached to the tactical load bearing vest.
LCS-84 tactical load bearing vest / ABA load bearing vest set up:
Both vests have four 2-inch D-rings on the back. Simply thread the 1-inch web from the tactical pack through these four D-rings; then attach back to the lower two Fastex buckles on the tactical pack. (See pictures)
Tactical Load bearing vest (LBV-1988) set up:
The vest has no D-rings at the top, and the bottom D-rings are located at a higher position than the LCS-84 TLBV. Simply thread the 1-inch web from the tactical pack through the 2-inch webbings at the shoulder pads; then through the bottom D-rings and attach back to the lower two Fastex buckles on the tactical pack. (See pictures)
As regard to the Delta Force photo (1989), the LBV used seems to be the LBV-1988 as the bottom two D-rings at the back of TLBV are located at a higher position.
Pictures also feature a comparison between two tactical packs:
Woodland camo experimental tactical pack 1986
Olive Green tactical pack LCS-84