Brute force knowing some characters (but not their location)

[Snoopy]

-a 3 -1 '?l9' '?1?l?l?l?l?l?l?l'
-a 3 -1 '?l9' '?l?1?l?l?l?l?l?l'
-a 3 -1 '?l9' '?l?l?1?l?l?l?l?l'
-a 3 -1 '?l9' '?l?l?l?1?l?l?l?l'
-a 3 -1 '?l9' '?l?l?l?l?1?l?l?l'
-a 3 -1 '?l9' '?l?l?l?l?l?1?l?l'
-a 3 -1 '?l9' '?l?l?l?l?l?l?1?l'
-a 3 -1 '?l9' '?l?l?l?l?l?l?l?1'

I meant:
-a 3 '9?l?l?l?l?l?l?l'
-a 3 '?l9?l?l?l?l?l?l'
-a 3 '?l?l9?l?l?l?l?l'
-a 3 '?l?l?l9?l?l?l?l'
-a 3 '?l?l?l?l9?l?l?l'
-a 3 '?l?l?l?l?l9?l?l'
-a 3 '?l?l?l?l?l?l9?l'
-a 3 '?l?l?l?l?l?l?l9'

well depends on how much chars do you know to reduce keyspace

also depending on the hashalgorithm, for fast algorithm like md5, you could simple stick to

-a 3 -1 '?l9' '?1?1?1?1?1?1?1?1' in your case, as one char/sign more is peanuts for a fast hash

23^8 = 78.300 million
24^8 = 110.075 million

knowing more chars will change this