I had a problem with my trans in my 84 which occured without notice.  
I was unable to get it into 3rd 90% of the time, even when the engine 
was not running. <-- This is a key diagnosis point. There is a component in the trans which is known to 
break, called the 'operator sleeve'.  There are two, one for the 1-2 
gears and one for the 3-4 gears.  It is a cog gear thing with a 
sliding outer disc, about the diameter of a beer can.  There are 
stress points which crack and the inner sleeve then starts to flex 
not letting the outer sleeve slide freely.  When you apply pressure 
from the shifter it won't go out of gear because it's flexing rather 
than sliding.  Sometimes you get lucky and it goes, sometimes it just 
breaks, kaput.  In Canada the part was around $450 Cdn, and the labor 
is about 8-10 hours.  I did the clutch while I had the thing apart so 
add another $150-250 for parts, plus I did some synchro rings also 
($25).
The other thing is the pilot bearing which some people have been 
having trouble with.  I think it's much less to repair.  Good luck.

Brian.

Steven wrote:

> 
> I was driving along in my '85 with a manual 4sp. While in third gear I 
> came to a stop and to my horror I could not get it into neutral. After 
> frantically working the lever I was able to get into neutral and then 
> into first gear. While doing this I encountered great resistance and 
> the familiar H pattern went away only to be replaced by a nebulas stiff 
> mush. Yuck! Things seemed to settle into place again and I was able to 
> get home but 4th gear was not available. Later last night I was able to 
> get into 4th gear but only with great difficulty. What's going on?
> 
> Steve
> 
> 
> 
>