The Micro Minnies started using Dexter axles in August of 2020 (2021b models). I believe the prior axles were from Lippert, but I’m not 100% certain. They may have a similar zerk for adding grease to the bearings.
The EZ-lube approach (grease zerk) makes a lot of people nervous, as there is some risk that you’ll have grease get past the inner bearing seal and into the brakes. Others have had good luck with the approach.
2021b Micro Minnie 2100BH
2017 Ford F-350 SRW diesel