John Deere must have made a change to the tilt steering sometime fairly early in production. The first 4X20 series tractor I saw had the rubber cover tilt handle that you described and had hard plastic covers over the mechanism. The covers moved with the tilt and you could see past them into the area under the dash. Later 4X20 tractors use the tilt with the metal handle you describe and the rubber boot over the column. I wonder if any 3X20 tractors ever did use the earlier version. Operators manuals are prepared using preproduction tractors so the change might have taken place by the time 3X20 production started.