I used 1/4" plexiglass for mine. 2" hole for the fan.

 

I have a piece of that plastic wall/ceiling covering they use in kitchens/bathrooms, works GREAT. Have a 6" center hole.

CD

 

Seems most of you guys have 2nd Gen 12V and 24V trucks. I've never ran anything in front of the radiator on my '07 and it has no problem getting up to temp or maintaining temp, down to about -20degF. Never been colder than that with this truck.
High idle does help it warm up a bit quicker the few times it sits out overnight in the cold.
Only time I've had the cold weather pull temp down is coming down a LONNNG grade out of the Eisenhower tunnel. No fueling for almost 10mi. EGT's were under 300deg and temp guage dropped all the way down.
I need an exhaust brake!

 

I think because of the higher hp and torque the common rails get warmer (engine temps). My 12 valve has a hard time getting over 180degF when its cold outside and unloaded. However, I had my old 04.5 up in WY a couple years back in a nasty blizzard maybe around 0degF, maybe -5degF or so, and noticed that the heat in the cab was not quite sufficient. After that I started using cardboard in between the rad and in.cooler. Not only does it help with cab heat, but it also heats the up A LOT faster on cold mornings! Try it, I think you'll agree.

Scott

 

helps to be able to keep her inside. Mine takes the entire 15 miles to work before the t-stat opens for the first time. high idle is cool but it takes forever for my truck to get up to temp. I am going to cardboard it tonight or buy a piece of plastic like CD in NM does or swing by my buddies trucking shop and steal a mud flap! LOL

 

Once it starts hanging about 0*F I pull the fan and leave it off. It's a bit trickier with a manual trans but still doable until it starts going over 10* or so.

When I had a 93 with an auto. I could run without a fan and a completely blocked radiator until it stayed over 30*F. The tranny heat exchanger would help keep the coolant temps in check and the trans temps as well. I did have the aux tranny cooler under the bed though.