Ahh, I ddin't search in the notes field for the chassis when I didn't find it in the chassis field, i'm rusty at this. so 113-657 was originally fitted with chassis 25307310b when it was built as a FFT. It was converted to a LRPV at some stage, and along the way, before or after the LRPV conversion, it was given a new chassis from 177-141. The original chassis must have been repaired along the way, possibly under 177-141 or another vehicle, but never recorded in the ARN Ledgers.
Well, that's how I see it. Doesn't quite help with the actual ARN/Identity though, just where the chassis was originally.