If the bearings have never been serviced, they should be removed and inspected BEFORE you do the Zerk fittings. Who ever does your bearing inspection/repack and new axle seals can verify you have Ultra-lube axle spindles at the same time. Once they are packed and the Zerks installed, you can use the flow through lube change without worry.
Lou and Laura with Bella - German Short Hair Pointer
2008 GMC Sierra 2500HD Crewcab SB Allison Duramax
2010 Flagstaff 8526RLWS - Superglide 3300
HAM CALLSIGN - KC3FFW