That's very interesting, 180. Do you suppose a 105.51 was ever fitted with aluminum? I have a couple of Retail Parts Books to look up the parts numbers. I think the Competition Handbook had parts numbers too. (-99 suffux numbers.) Do you suppose the 105.51 sitting in my garage could have been originally fitted with aluminum, then some unknowing person replaced the aluminum with steel. (Leaving me in the position of having to refit aluminum panel only restore it for "Originality" . Would you believe . . .