To open or extract the data within SPECIAL992_PACK1.part1.rar , you must have all other parts in the same set (e.g., .part2.rar , .part3.rar , etc.) in the same folder [1, 2].
Simply use a program like WinRAR , 7-Zip , or similar to extract only part1 . The software will automatically pull data from the subsequent parts.
Do you have (part2, part3, etc.) in the same folder? What software are you using to try to open it?
Are you getting a (e.g., "CRC error," "unexpected end of archive")?
Do not rename the files, as they are numbered sequentially.