*Drive it like you stole it?
Seriously though..Shift without the vehicle running, and when going into 3rd or 4th, listen for a thunk or clunk indicating the countershaft is loose.
Start it up, take it for a drive and get it warmed up, as it'll shift a bit off when cold. It's normal to have it hard to go into first sometimes, same with reverse. Put it into first let the clutch up slowly and let it catch up. Same for reverse, put partially into first, just don't release the clutch fully, depress the clutch and it should shift easily into reverse without any light grinding.
*It seems that all Toyota Truck transmissions do this bit.
Put the e-brake on, shift into neutral and see if there's any noise like a pilot bearing going out. Now, depress the clutch and shift the case into 4-hi and release the clutch. There should be no excess effort needed and only a little noise from the countershaft slowing down.
Depress the clutch again and go into 4-lo, same stuff to listen for.
Now shift the case into neutral, there will be some light noise, if it seems excessive it can be bearing noise.
Put the case into 4-hi or 4-lo (*if on wet pavement or a dirt road), or even 2-hi and take it for a spin. Then when around a dirt road/whatever, or even a wet road and put it into 4wd and listen for the (*if equipped) ADD hubs to lock, or lock the hubs and they should engage within 5-7 feet. *Never run 4wd on dry pavement, the 50/50 split will tear up stuff quickly if not experienced in driving in that condition.
Unlock the hubs, then shift back into 4-hi and do the same. Then go into 2-hi, stop and unlock the hubs (*if manual hubs disengage them) roll in reverse and the hubs should disengage.
Park in a good spot and rotate the front driveshafts, listening and feeling for grinding or binding, turn the wheels to full lock left, but don't force/hold it there, get out and do the same and repeat at full lock right.
The shafts should not make any noise or feel odd. They should also not shift in or out of the hub much, if so it may be jst needing a new thrust clip and shim, but there's more to it if that comes up.
**I'm surprised Wristy or 2ndGenToyotaFan didn't jump all over this subject, is this in the FAQ's, if not it should be.
