3 speed shifts into 1-2-3 fine, but grinds into reverse

[Tilt]

I have an 86 with the 4.3 V6 with 3 speed column shifter. It will shift into 1-2-3 fine with no grinding, no matter if I'm parked or driving down the road. When I try to shift into reverse, it just grinds. To get it in reverse, I have to either jam it in or put it in 1-2 or 3 and dump the clutch and kill the truck, then it will go in just fine. The pedal feels good, clutch releases at just over half pedal, the shifting fork moves roughly 1"-1.5". Any ideas as what I need to look at/for?