The '84 CD is indeed a W123-bodied car. It is mostly the same as a sedan and the front is identical to the sedan and T-sedan (wagon) with the obvious differences related to 2 doors vs. 4 doors, etc. The front seats are different since the backs need to tilt; I think there's a pressure or vacuum-actuated safety switch to "lock" the seat backs in place when the car is in motion.

The front doors are longer, the rear seat may be the same. Most of the electrics will be the same, the trunk sheet metal and hardware should interchange. The front end and engine will swap except that the T-sedan's engine has a special pump for the rear shocks.

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"Buster" in the '95

Our all-Diesel family
1996 E300D (W210) . .338,000 miles Wife's car
2005 E320 CDI . . 113,000 miles My car
Santa Rosa population 176,762 (2022)
Total. . . . . . . . . . . . 627,762
"Oh lord won't you buy me a Mercedes Benz."
-- Janis Joplin, October 1, 1970