To adjust your shifter correctly
1. Start by installing the levers only on the transmission (numbers/letters facing out). Use blue loctite and lighten the nuts to 200 inch pounds. Find neutral position for the 3/4 lever (front top lever) and the 1/2 lever (Rear top lever). Move the reverse lever (Bottom lever) all the way forward. This centers the internal transmission parts.
2. Align the shifter indexes (right under shifter body) many OEM reverse levers are not drilled for an alignment pin.
3. Adjust the rods and swivels to the shifter arm and transmission arm holes without moving either arms.
4. If there is any binding you may be one turn off one way or the other. The center of the shifter has to aligned very close because of the transmission interlocks and shifter arm pass throughs.
Picture of O/D linkage
View attachment 1716093342
I've done all this many times over . Talking to brewers and few other folks the general consensus is it's the shift mechanism itself jamming . Not the rods adjustment as it's set just as you and all the experts say. The shifter mechansim binds . But I can move the shift tabs & rods easily by hand but the shifter with no amount of wiggle : banging or pushing will unstick it . But two fingers on the rod can with ease . This tells me and other that it's not the trans itself but the mechanism . I pulled reserve rod totally off and still Jams , pulled 3/4 off and still jams. The shift mechanism what I'm seeing in videos and sent to some folks is just way rattly and loose and sloppy. I'm going to buy a new one I guess . No worries . Part of buying old used stuff