Well, the 77 240D leather seats look great in the 74 450SE. Although the tracks/mounts didn't fit perfectly they were easily adaptable.

All I had to do was peel back the carpet piece pver the front mount holes, move the clip/j-nuts from the rearward slot forward a couple inches to the front slot, and finally drill a new hole in the track about an inch back from the front hole. After this they bolted right in and work great!

Justin B.