It is a 123 chassis, with the early 616 engine of the ones used in the 123 family. As far as I've seen the 80 model year was split with some early cars having the earlier engine and the late 80 cars having the later engine. The early engine had about 3 less HP.

Your car also probably has a brass radiator, loop type glow plugs (which are commonly converted to pin type,) the Chrysler climate control unless you are lucky and have manual a/c controls, cast door straps instead of the later flimsy stamped sheet metal ones, a two cylinder York type compressor mounted on the passenger side upper, and probably an 85 MPH speedometer.

There are numerous other detail differences between the early 123's and the later ones, but one is as good as the other IMHO. There are advantages both ways. I drove my 77 only 286,000 miles. By that time I figured out just how long lived they could be so when I got my 84 Euro 240D I took MUCH better care of it and it topped a half million.

Enjoy,