will not go in 4 th geer on 1991 Mazda B2600

it is a 1991 mazda b2600 le-5 4x4 will not go in 4th geer it has a new clutch in it and the clutch peddle is close to the floor it does go in all other geers

Asked by for the 1991 Mazda B2600
I find that a very good test is to turn off the engine and with your foot OFF the clutch pedal, try shifting all the gears, if you can easily shift all gears then the problem is somewhere in operation of the clutch, if you have trouble, then you have a transmission or shift linkage problem.
I learned this from factory classes, I used to rebuild manual and automatic transmissions at Dealerships.