I have an 88 F350 with a 5-speed trans that lost 1st and 2nd gear. All of the other gears work as they should. When I put it in 1st or 2nd it feels like it clicks into gear but when you let the clutch out nothing happens. Any ideas of what this may be?

 

It sounds like the 1-2 shift fork is worn to the point that it doesn't move the slider ring. The shift rail detents will make it feel like it clicks into place but the fork isn't moving the slider ring to engage the gears.