Here is a link to decode your carb numbers. I also recomend them as a source for rebuilt carbs.
http://www.carburetion.com/quadnumber.htm
Here is how your carb number plays out
17058213
1705 - 1976-79
8 - year built 1978
2 - carb type - 2 = quadrajet
1- car model - 1 = Chevy
3 - transmission type - odd = manual, even = automatic
The second number you listed did not check out.