So I replaced my old w55 with a known good w58(pulled from my dads truck a year or so ago). While we were at it we replaced the clutch with an OE clutch and used Redilne MT90 GL4 fluid. 1st, 2nd, 5th and reverse all go all the way in. 3rd will go partially in and pop out and 4th will just grind if I let off the clutch. Now if I shake the shifter a little while shifting, it will fully engage both gears with no issue.

1st, 2nd, 5th and reverse are all super tight, zero movement from the shifter, 3rd/4th are both a little sloppy but not bad.

I did reuse my shifter linkage and housing and the bushings from my w55. The shifter seat bushing is pretty soft, but I had no problems getting all 5 gears on my w55, so I am at a loss as to whats going on. Any ideas?

 

What's in common between 3 and 4...selecter fork, selecter shaft...the part where the shifter meets the shaft. a little bit of play makes a big problem once you factor in the leverage.