can't say about what was original for sure, my 46 big bolt had a chrome bumper, but I do know there are about a dozen different 300 series SS numbers - 304 is the most common and likely the only one used for parts, 316 is the food and surgical grade, which has the highest corrosion resistance of the 300 series, but stainless is "corrosion resistant" not "corrosion proof", any SS will corrode under particular conditions
Bill
