trunnion bearing

The stock trunnion is rubber-isulated steel while your aftermarket one may be aluminum with a teflon bushing. Because its pretty hot under the headers, teflon is not a good choice. The teflon bushing makes shifting easy and no lube is required but the bushing is held in with a setscrew and heat will allow the teflon to slip past the setscrew and bang!-you get REALLY sloppy shifting! Its possible to fumble the loose bushing back in place without removing the trunnion, but this will likely be an ongoing problem. Over-tightening the stscrew doesn't work either 'cause you'll just shove it clear through the soft teflon.
To remove the OEM unit, any gear is OK. Use a flat blade screwdriver to slightly spread the halves of the shaft connections to the gearbox and the u-joint. All this stuff is metric so don't try usind SAE wrenches or you'll just strip things out. A good idea is to spray the connections with cheap paint before removing things so when you reassemble, you have some reference point. Shifter adjustment is outlined in your red owners manuasl and should be followed EXACTLY or worse shifting than you now have will result.

Mark, that is the type of bushing that I have already bought. But based on what Jack says above, it doesn't seem to be too useful, other than for a cigar holder or big roach clip. I have not put it in yet, so I don't know if I will experience problems or not. Probably should have gone with the bearing unit instead of the bushing. I plan to give it a try though, as I am getting real hung up everytime I try to get into reverse, despite going into another gear first.