OK as I seem to talk to myself, I found a workaround for the time being.

I keep cross_sell__just_another_cross_sell_mod_rev186 installed and just added the older Cart Upsell/CrossSell on Shopping-Cart Page mod back into my new 1.3.9h install.
http://www.zen-cart.com/index.php?ma...roducts_id=283

Looking at the files, there should be no major draw back using these two mods instead the Ultimate here.... at least I have now cross sell and upsell functioning. Still, I would be very interested to learn how to migrate to this Ultimate version.