It's got to be the roof-rack. The W124 body was not altered in any way, except when it was lowered and the front end was narrowed in 1990. Then in '91, the sedan got a 'flat-butt' rear-end. Maybe the wagons rode a bit higher in the '90's then the sedans. But not in the '80's.
My sister has an '89 300TE, and an '87 300D. Except for the roof-rack, they are the same height.
1987 300SDL (324000)
1986 Porsche 951 (944 Turbo) (166000)
1978 Porsche 924 (99000)
1996 Nissan Pathfinder R50 (201000)