1987 SDL transmission problems.
 

- Transmission does not want to go to 3d and 4th gear.

- Will go to 3d at around 2800 rpm.
- Will go to 4th at around 3500 rpm.

- Disconnected kick switch and no effect.

- Car is 1987 300 SDL with around 250,000 miles and original transmission.

5th gear? Really?
 

5th gear in a 300SDL?
Are you talking about REVERSE?
I've never driven a 300SDL that had 5 forward gears.

^^^Hmmm Whuuuuuu?
 

I'm confused. Aw, prolly an edit.

OP - Fluid. The answer is in the fluid. Check the level as outlined by MB.

Just went through this a week ago. Yep, you got it, was low fluid.

Also a suggestion: the search function near top of page will answer your query faster than waiting for replies to be posted.

MBZ123