ok, 5 speed transmission stuck in a gear?...

ok so you say it is common when on stands...but...with the truck on the ground, when I start this truck in neutral, I push clutch pedal 'in' to crank...but, 'I cannot let off clutch, it'll cut off... although the shifter and transmission looks like it's in Neutral, it's obviously in a gear...with the truck on the ground, motor running, and shifter in neutral position, can't let off clutch...

Now that's a different story! .. Remove the shifter, using large screwdriver re-align all shift fork rails back into the neutral position, using caution, start engine to be sure transmission is indeed in neutral .. Re-install shifter.

I made sure rails were in neutral, but it still seems in a gear instead of neutral... don't know how to add image link or I'd show you picture of shifter removed and rails, as far as I know lined up in neutral

Don't forget about the reverse idler, the small gear, make sure it's not engaging another gear! .. Can't post any images on this site.. You may need to get some hands-on help with it.

is this reverse idler accessible from top at shifter, or does transmission need to be removed to get to it?...

Use a good flashlight to look into shifter socket/cavity .. Now imagine what action needs to take place to shift to reverse by using shifter sequence in your head .. You should be able to see if the idler is engaged .. Also should be able to use slim screwdriver to move idler, if needed .. Good luck with it!