Hi all-
Have a good condition 84 300dt, the transmission has been acting up in the following way:

It L, it doesn't shift
In S, it shifts once
In D, it shifts twice

Which means I'm reaching 3rd gear and no higher (or so I assume- my tach isn't working, but it has seriously high revs at 55-60).

I bought the car a month or so ago, and don't have occasion to take it on the highway all that often, and this week was when I first noticed. It seemed to cruise at 70 fine when I bought it. Fluid level seems fine (and clear, pink) despite a persistent small leak (just add a little fluid every week).

Any ideas? Thanks-