Hello stewypup68 welcome to the group,
That is a hard question to answer in a meaningful way. I would imagine going from 3.42 to 3.73 would be worth a few tenths.
For whatever it is worth when I swapped my diff from 3.15 to 3.42 in my 370rwhp C5 I went from 12.6 in the 1320 down to 12.3.