The following article describes installation of a genuine Ford accessory engine block heater on a modular engine equipped Ford panther platform vehicle ('91+ Town Car / '92+ Crown Victoria, Grand Marquis and Marauder)
The general procedure is the same for most engines, however.

Block heaters are beneficial in cold climates for faster starting and warm-up time by heating the engine block / coolant using a 110VAC electric element.

The following article was authored by luv-my-2002-p71 and was originally posted in This Thread

Well I installed the block heater. Just coming back to update the thread. I bought one from a member here. It's a nice brand new genuine FORD block heater.

Step 1: drained all of the coolant from petlock

Step 2: Jack up car good and high.

Step 3: Find the drivers side rear frost plug. Someone here (JohnG) said that's the one they tap into and use from the factory. It is very easy to get to compared to the others so that's perhaps why plus less heat to cook the cable over time.

Step 4: Take a hammer and a large flat blade screw driver and put the flat blade on the edge of the frost plug. The frost plug is fairly thick aluminum. You want to hit it on the edge in such a way that it pivots. I hit mine like 10-15 times before it started moving inwards. - you will get wet. Use a drip tray.

It didn't really want pivot. The whole frost plug went into the block!!! No worries though there is a shelf type thing in there and it won't really go anyware. I took a pair of channel locks and grabbed onto an edge of the alumimum frost plug and it pulled out easily.

Step 5: put a little pit of WD-40 on the new block heater gasket (really the whole thing) Slid it in there.

While holding/pushing it in firmly. I took my small socket wrench and started tightening the center bolt of the block heater which forces the sides outward as it's tightened. I tightened it snugly and then did about 2-3 more turns, used about 5-7 pounds of pressure (just guessing - no torque wrench used) If you go godzilla tight you will break your new frost plug. Look at the assy that holds it in first and you'll see what I mean.

Step 6: Remove goose neck and t-stat and filled engine/block with coolant, took about 1 gallon.

Step 7: Filled up Radiator with 1 gallon of coolant. 50/50 mix, I used prestone. In a perfect world I'd have used AMSOIL coolant (FTW)

Step 8: topped off with about another 1/2 gallon of coolant.

A day later the coolant in the resivour looked a bit low, but not like "holy crap it's leaking low" I topped it off again, and let some of the air out while it was still warm.

No leaks - looks good.

I think the reason the rear drivers side is used is the major heat from the headers. The Ford block heater has a heavy insulated jacketed cable with wire loom all over it.

I zip tied it away from the heat and then up and over the engine to the passenger side. I have the plug hanging out of black honey comb grille. The cable has a "quick" disconnect part so that in the summer you can disconnect the cable and then pull out about a 2.5 foot section of cable out through the honeycomb grill. (as the plug receptacle is too big to go back through the grill into the engine area)

Ask any questions. Apparently there aren't many who've done this on CVN..

FYI: The Part number (now discontinued) is XR3Z-6D008-DA -- This is the Kit that I installed - works great.
This is for both a 4.6 and a 5.4 block.
There is another Ford partnumber: 1R3Z-6D008-AA and this is listed to fit a 4.6 Ford engine whose description is:
Description: In addition to the engine block heater, this kit contains a battery warmer that wraps around the battery. Once itís installed, simply hook it up to any heavy gauge extension cord (not included) and plug into a standard wall outlet.

-------Courtesy luv-my-2002-p71

Refer to the image and caption here for more tips, courtesy Steve83:
-Panther info & FAQs-

Former owner of a Grand Marquis with a few mods, Grand Marquis "LSE S/C"