To solve this expression, we need to follow the order of operations (also known as PEMDAS).

First, let's simplify the expression inside the parentheses:
6 - 1^100 = 6 - 1 = 5

Now, let's simplify the expression inside the brackets:
29 - 5 = 24

Next, let's simplify the expression outside the brackets:
24 / 2^3 = 24 / 8 = 3

Therefore, the final result of the expression 129 - 5 . [ 29- ( 6 - 1 mũ 100 ] :2 mũ 3 is 3.