Easy forms!

local events = CreateFrame("Frame")
events:SetScript("OnEvent", function(self, event, ...) return self[event](self, ...) end)

function events:UPDATE_SHAPESHIFT_FORM()
    if not tMorphLoaded then return end
    local form = GetShapeshiftFormID()
    if form == 1 then -- cat form
        SetDisplayID("player", 38150)
        UpdateModel("player")
    elseif form == 5 then -- bear form
        SetDisplayID("player", 43759)
        UpdateModel("player")
    elseif form == 31 then -- Moonkin form
        SetDisplayID("player", 45941)
        UpdateModel("player")
    end
end

events:RegisterEvent("PLAYER_ENTERING_WORLD")
if UnitClass("player") == "Druid" then
  events:RegisterEvent("UPDATE_SHAPESHIFT_FORM")
end