I sell a axle/bushing kit that has tapered axles and bushings both for the knuckle and link couplers. Take a look at my web site as I also have a video that shows before and after and it really improves the rolling power of the cars. www.goldinhands.com/american_flyer_wheel_bushing.htm
The improved roll-ability is amazing – great demo video, thanks Ed.
I wonder if the eyelet is necessary with a link coupler truck? And I'm still curious about nylon bearings.