Well, without seeing the actual serial number of your carts tag, I feel safe to say that your serial number tag is aluminum, and I'm willing to bet that your model number on the tag is either E0901 or E0900, most likely E0901. If I were to guess, I'd say the serial number will be between 50,000 and 52,500. If I'm correct, that would place your cart around the early to mid 1971 model year range.
Please post a picture of your serial number tag when you have the chance, which will be located on the front face of the cart, just above the "80" decal. Thanks for sharing!