Specifying package names
A package can be referred to for install,update,list,remove etc
with any of the following:
name
name.arch
name-ver
name-ver-rel
name-ver-rel.arch
name-epoch:ver-rel.arch
epoch:name-ver-rel.arch
For example: yum remove kernel-2.4.1-10.i686
Eu acho que você extraviou {arch} deve ser, finalmente, a sintaxe correta é:
yum install <package_name>-<version>-<rel>.<arch>
Tente:
yum install body_guard-0.2-0312.x86_64