3 speed column shift grinding in 3rd-Help!

[hulleywoodworking]

I rebuilt the 3 speed light duty remote shift transmission for my 51 F1, replacing/installing the following:
NOS Main Drive Gear
NOS Reverse Idler Gear
New Reverse Idler Gear Shaft
NOS Reverse and Low Sliding Gear
NOS Cluster Gear
NOS Cluster Gear Countershaft
New Synchronizer Block Rings
New bearings, spacers, thrust washer, seals, etc.
Clutch, Pressure Plate, and Throwout Bearing rebuilt by Fort Wayne Clutch
Flywheeel turned when engine was rebuilt.
Fresh 80W-90 gear oil, filled to correct level.

So pretty much a new transmission. I assembled it following the Service Manual AND with plenty of research online. The synchronizer block rings were set as per Mac Van Pelts directions, which I found on the web, so I know that the spacing is correct there.

I have the truck up on jack stands as I am still putting it all together. I adjusted the clutch pedal linkage so the arms on the throwout bearing are less than 1/8" away from the 3 pressure plate arms. I adjusted and re-adjusted the remote shift linkage so that it would shift smoothly without the engine running. I started the truck and tried running through the gears. 1st from Neutral fine-1st to 2nd fine-2nd to 3rd a little bit of grinding before it would engage-and any gear to reverse ok if I went through Neutral first. All gears spin the rear tires, and Neutral is just that-neutral.

After screwing around with the adjustments multiple times, I cannot get it to NOT grind going into 3rd. What am I missing?

Is it possible that it grinds because there is no load on the wheels/drivetrain? Or is there a problem here?

Any help would be appreciated.

Thanks,

​​​​​​​John