For openSUSE Tumbleweed run the following as root:
zypper addrepo https://download.opensuse.org/repositories/mozilla:legacy/openSUSE_Tumbleweed/mozilla:legacy.repo
zypper refresh
zypper install MozillaFirefox-branding-openSUSE
For openSUSE Leap 42.3 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/mozilla:legacy/openSUSE_Leap_42.3/mozilla:legacy.repo
zypper refresh
zypper install MozillaFirefox-branding-openSUSE
For openSUSE Leap 15.0 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/mozilla:legacy/openSUSE_Leap_15.0/mozilla:legacy.repo
zypper refresh
zypper install MozillaFirefox-branding-openSUSE
For openSUSE 13.2 run the following as root:
zypper addrepo https://download.opensuse.org/repositories/mozilla:legacy/openSUSE_13.2/mozilla:legacy.repo
zypper refresh
zypper install MozillaFirefox-branding-openSUSE