Slitherine

I assumed cost for upgrade within a "family" was less than when changing - so for Mk.III its cheaper to go to upgrade of another III instead of changing to Mk.IV.
But from StuGIIIB to StuGIIIF costs 299 points (and SS counterpart 329 in SS Elite Mod) - same Mk. or not? Changing to Marder IIA costs 262. Dont understand...

In the base game you cannot upgrade a StuG IIIB to a IIIF, because they are in different categories (artillery vs. antitank). So I guess this is while using a mod? If so, the modmaker did not put them in the same upgrade family, and that's why youy have to pay full price. You could post this in the relevant mod thread, it might be a small oversight.

Ah yes thats it - sorry... its the SS Elite Mod which gives a formidable StuGIIIB in AT role