I'm gonna start on the entrance and work my way as best as I can around the park.
As you enter the park, the architecture of the monorail, guest relations, ticket booths, flower beds, planters, trees, pavement etc, almost all of that is original from 1982, including some of the various singage.
Once you get into the park's entrance, the two flower beds on the outside most paths are also original as well as their surrounding architecture.
Spaceship Earth of course, as well as the mirror column.
The Earth Station, now that its project tomorrow...the only thing really left from earth station is that project tomorrow once again has alot of space and openess in it, something only earth station once had.
The Communicore Buildings are that ugly tan, pinkish color, with many of the windows blocked out with posters. However the exterior of Innoventions West still has the original lamps on the side of the building.
The Seas was from 1986 so that doesn't count. Nothing really left from Imagination except the basic look of the building, the jumping fountains and lamposts. The Land still had the baloons, though they were repainted, and it also has the mosaic tiles, and dedication plauqe called "symbiosis". Parts of living with the land, and the circle of life theatre and queue area are original from 1982 if memory serves me correct.
The circular fountains of future world west are original as well.
On future world east....wonders of life doesn't count, nor does mission:space, the energy pavilion has the original theatre cars, mosaic lobby mural, fountains outside it, etc.
Test Track....the car from world of motion was in the turn of the 20th century...it was the guy using the hand crank to start the car.
The Transcenter...or inside track....some of the chrome and silver is leftover from the Transcenter as well as come of the platforms used to showcase the cars.
The Odyssey is original from 1982.
Much of World Showcase is original from 1982 except for Norway and Morocco. You can still see Impressions de France, another 1982 original.