Use dictionary word anywhere in the mask

[badagaga]

Hello,

I can't find the answer to this question in the wiki but maybe I'm not searching with the proper terms.

I'm trying to find out how a specific 8 hex digit hash/checksum is generated by a closed-source program.

I'm pretty sure the build number of the program (e.g. "104") or maybe the full version number (e.g. "2.1.104") is part of the input when this checksum is generated.

Question:
How would I use the string "104" as a dictionary word in hashcat without specifying its position in the mask, so that hashcat increments in the following way:
104?a
?a104
?a104?a
104?a?a
?a?a104
?a104?a?a
?a?a104?a
?a?a?a104
104?a?a?a
?a?a104?a?a
...

I've looked at hashcat's rule-based attacks but I don't see anything about this type of rule. Is this even possible?

I understand that hashcat was designed to crack passwords. Are there better tools out there to help guess the input strings of checksums when I have a plaintext file that I know part of which were used to generate the checksums but don't know exactly which parts?