Transmission Gurus - Need to "Warm Up" gearbox?

Vehicle: 1997 Nissan Pickup (yeah, but it’s paid for)
Drivetrain: 4 Cyl with 5 speed stick.
175K miles

Lately, when starting, I can’t shift it into ANY forward gear, and trying reverse produces an unpleasant grinding noise. This goes away after running for 3-5 minutes, and once driven a block or so, everything works as it should.
Transmission fluid level is fine, no gross contaminants (like brass) visible.
Any ideas?

Hydraulic assist for the clutch, if so equipped, could be low or out of fluid. Would make cold shifts a real B|tch. But I think you are looking at a clutch issue.

My car is tough to shift in cold weather. Where are you?

Sounds more like a clutch problem.

I’m in Sacramento - we don’t do really cold - this is 60-something degree F.

Yeah, the clutch is a weak spot - will check the fluid tomorrow - until I checked the manual, I had no idea it was hydraulic.

Oh - I forgot:
Thanks!