The 1989-1996 Japanese broadcast had unique sound effects (different kiai shouts, original TV background music cues) that were replaced on home video due to copyright issues with composer Shunsuke Kikuchi’s original score. This REPACK preserves the on a 1080p upscale.
This number is likely a or a fan-group internal numbering . In the world of P2P groups, episodes are often tagged with their absolute episode number in the original Japanese run. Original Episode 258 is titled "Buu’s Miraculous Transformation!! The Birth of Gotenks" (or similar depending on the translation). This is a pivotal episode where Goten and Trunks finally perfect Fusion and Gotenks is born. Dragon Ball Z -1989- - S09E05 - 258.mkv REPACK
This is the most important word. In release groups, a REPACK means the original release (the PROPER or initial version) had a critical flaw. The group has re-encoded, re-muxed, or re-uploaded the file to fix it. Common reasons for a REPACK include: The 1989-1996 Japanese broadcast had unique sound effects