300d or 300sd

[blackestate]

Looking to replace my wrecked 300sd, 81.

I have found an 84sd, a little rough. But ok.
And for the same price I found an 81 300d. Looking much better.

I have stuck with the sd due to having spare parts for all cars made easy. But I am thinking hard about the 123. I like the front better.

How much stuff will interchange between these cars?
I have never driven a 300d. is there the same ammount of room for the driver

Kind if a weak question, hope you can see what I am thinking....

Thanks