it would be peaches if someone with a 12" fan wanted to do the same and mount a 10" in his a/c shroud and thus sent me his 12" fan blade...I of course would send him back my 10" one.

 

Scott,

I've try on an 12" slim fan on the factory shroud, this is how it looks!



Best size to use, 13" on main fan, and 11" on the A/C side fan.

 

I ended up having to remove the fan from my main shroud. I wouldn't suggest using the stock shroud unless the blades fully extend.

I still have the 10" on the a/c side. However after seeing how two 12" fans fit together on the rad even without shrouding, I'd just go ahead and zip tie those bitches to teh face of the rad and be done with it.