Download the appropriate zip for your system from the latest release
Unzip the archive and you should be able to find gguf-split
Locate your GGUF chunks folder (ex: Meta-Llama-3-8B-Instruct-abliterated-v3.Q8_0)
Run gguf-split --merge Meta-Llama-3-8B-Instruct-abliterated-v3.Q8_0/Meta-Llama-3-8B-Instruct-abliterated-v3.Q8_0-00001-of-XXXXX.gguf Meta-Llama-3-8B-Instruct-abliterated-v3.Q8_0.gguf
Make sure to point gguf-split to the first chunk of the split.