I have come across an 86 sdl turbo diesel that a 90 year old man is selling. It has 66,000 original miles, and it has been sitting for the past 4 years. The interior is almost perfect, the paint has one section that is faded. He wants $3k. Is it a steal?

I am unfamilair with this engine, I have searched to no avail, is this engine better than the one in my 81 300sd turbo? How do these engines take to veggie oil? Should I do something special to start the engine for the first time in four years or just crank away?
I probably can't do anything too major since I have not purchased it (yet). Anything in particular that I should specifically look for besides the obvious stuff. Any advice is greatly appreciated. Thanks