This build is referenced in the information that came with 1721.3:
Dear Windows 98 Beta Testers,
We have taken the incredibly fast feedback we recieved on 1720 as well as fixes that were already in the works and we are closer than ever to RC1. We have implemented some core fixes which should help Power Management, Multimedia and Dial-Up Networking. We would like all of you to download this build if possible and give it a thorough run through.
Note: You do not have to download this build to stay active; this is an optional download.
This build is also mentioned in the Bits & Bytes volume 4 warez CD list but hasn't been found yet.
