I have a 1990 Nissan 4x4, 4 cyl, 5 speed manual.  It makes a
conspicuous metallic rattling noise in all gears, but especially first
and second.  Meanwhile, 5th gear is out.  I can put the stick into the
right position and it does not pop out, but it remains in neutral.  No
extra noise when this is done.  Also, getting it into reverse is a
little tricky but once done, it works fine.

4x4 works fine in both high and low, truck is well maintained and
clean and relatively low (140,000) miles, basically everything seems
fine other than the tranny problem.  And it drives just fine in first
through 4th, no apparent problems (although it would not surprise me
if I am grinding the rest of the tranny into dust.)

A guy whom I don't trust at all thinks it is a clutch bearing, but I
have my doubts.

I have not pulled the plug to look for pieces of metal but I plan to
soon.

So the way I see it here are my options:

- fix the clutch throwout bearing and hope against hope that it solves
the noise (probably wouldn't get 5th gear back, though);

- get a used tranny from a junkyard, and either install it myself
(amateur) or find someone with more skills than me who's willing to do
it;

- get a rebuilt tranny, with same two sub-options;

- buy a brand new tranny from Nissan, if available;

- change the fluid and pray that the pieces of metal get flushed out
and I am left with a vehicle with good working 1st through 4th and
reverse;

- do nothing, keep driving it until the transmission is totally
destroyed, and re-up my AAA membership so I can get a free tow when I
break down.

I'm looking for input on the merits of all of these options and
estimates as to cost.