Have you changed your mind yet about keeping it? If I bring another car home my wife might kill me, however, she knows that whenever I see, hear, or mention a W116 diesel I get the shakes.

Welcome to the Dark Side!
Today, open the hood. Pull back the vacuum line boot going through the firewall and vertical rubber "shroud" & inspect for rust. This is the low spot from hood & inner wheel well drainage. If you see any sign of water in the rear floor boards look in both hood hinge pockets.
Take a sharpie and write on your forehead "when inside anything that takes more than 1/2 hour to remove coverings, etc. VERIFY EVERYTHING IN THERE".
There are few frustrations greater than repairing a ft. window regulator just to have the vacuum lock go. OK repairing the ign vacuum line & forgetting the climate dashpots or cluster lights.
IMHO this is the best paint color for a 116. When buffed out it seems thick or solid, like the car was carved from a colored block of steel or rock
BTW: Your hood is and trunk lid maybe aluminum.
Do 0-60 time trial so you have a base line to gauge your tinkering results.
Now turn to Stuttgard and repete the 116 diesel matra, "I live for vacuum lines, GIVE ME MORE!" Someday I'll buy another clunker (mine is still going) and run vacuum lines to: turn signals, mirrors, visors, horn (s), license plates, ashtray, cig. lighter, hood latch, head light switch, washer, radio controls, fart sucker ... oh I forgot vacuum idle adjustment!
Driving a speed panzer just makes me grin in a world of lite weights. You should get 25 + MPG so let the little boys squeel.
Start dreaming of 250d's on streoids.

Thanks for the info on what to look for. Is there a way to re stuff the back seat? I know it can be done on the front seats. Also I know of a 450SEL that has the same color seats. They should fit right? I think the 450 is a 79 or 80

I pick it up Monday

Thanks