So my engine rebuild is just about complete on my 84 300sd. I am getting ready to turn my attention to the trans.

I have a trans out of a 83 300sd that according to the odometer only had 77000 miles on it (owned by a old man that only drove it on sunday, etc.)

I plan on using it with my rebuild, my current trans has 238000 miles on it.

I have never seen it work.

How do I determine if it is good and just how much work I should put into it?

As a min I figured fluid, and pan gasket and new modulator.

Should I just rebuild the whole thing?