This is what I use in KeepingTabs:
Lua Code:
if GetGuildTabardFileNames() then
f.ngt2:SetNormalTexture("Interface\\SpellBook\\GuildSpellbooktabBG")
f.ngt2.TabardEmblem:Show()
f.ngt2.TabardIconFrame:Show()
SetLargeGuildTabardTextures("player", f.ngt2.TabardEmblem, f.ngt2:GetNormalTexture(), f.ngt2.TabardIconFrame)
else
f.ngt2:SetNormalTexture("Interface\\GuildFrame\\GuildLogo-NoLogo")
end