Replace item in Sublist based on Index Number of Sublist

I’d like to replace non-zero items in sublists based on the index number within the sublist.

Sublists will always have items 0-4; replacement numbers will always be 20-24.

Original list of lists will be driven by selection of multiple Revit items, and will potentially be 20 sublists at a time.

New user, can’t upload .DYN file.

Got it working, thanks to reading some other posts.

Once I got the index numbers, I actually just had to add 20, rather than search & replace.