Pretty sure it's a Tan 14G fuse wire.
The FAIM does say 14R -red.
Is that why you're asking?
On my 69 diagrams I designed a few years back I designated this wire to be red as I didn't have an original bat cable on hand to verify the actual color. A recent buyer noted that my drawing had red and thinks it should be black. Now I'm curious as to what it should be. My purpose has always been to have available an accurate wiring diagram besides the "flawed" AIM diagrams.
A 68 Firebird I finished last year had a brown fuse link wire. I thought that may have been a Firebird thing; didn't think much about it!