"Steering feature" upgrade for set 2609 "LAV III APC" and 2610 "Stryker M1126 ICV"
Unfortunately it looks like Cobi is definitely discontinuing this cool feature, as the most recent vehicle releases 2609 "LAV III APC" and 2610 "Stryker M1126 ICV" sadly do not have this feature anymore, although there is nothing construction-wise that would have permitted this feature:
If you just need the "steering" parts, the cheapest way was to get the single "Battle of Berlin" issue No. 19 "Sd.Kfz.251 Hanomag" (5568). But unfortunately this issue is sold out now in the official Cobi webshop. I'm afraid I have bought the last 4 issues (for a total of 24 issues) for my spare parts collection.
So now the most affordable full set containing the needed steering parts is probably 2361 "Armoured Command Vehicle" (which also seems to be discontinued already, so get it while you can ...)