Hopefully this will help someone else that needs to R&R their radiator.
Remove 3 plastic allen head screws and pull off the black plastic cover over radiator header and headlights.
Disconnect wire and remove air cleaner box (pull up on end of box to free from rubber grommets).
Remove radiator cap and drain radiator (can cut lower hose to drain, if necessary).
Remove upper radiator hose (not necessary to remove lower hose from the radiator).
Disconnect wires from both fans and remove the 2 bolts from top of each fan that hold it to the header and lift fans out (held in at bottom by slotted rubber grommets).
Disconnect transmission cooler lines and plug lines.
Remove 7mm machine screw that holds A/C line bracket to driver’s side of radiator (hardest part of the job!).
Remove the two bolts that hold the electrical gizmo in the center of the radiator header and move it out of the way.
Remove the 3 bolts the hold the radiator header to the body and remove the header.
Remove 6 bolts that hold A/C condenser end brackets. There is one on the top of each end of the radiator and four on the front of the condenser. Lift and wiggle those brackets out (they have a tang that slips down into slots on each side of the radiator).
Lift out radiator. (note: good time to replace the front motor mount, if necessary).
Run water through the new radiator to flush it out, remove transmission cooler plugs, screw 7mm machine screw into boss on side of radiator to cut threads and then remove screw (makes it much easier to install later).
Reinstall everything in reverse order of these directions.
It is easier to replace all the GM hose clamps with aftermarket that you can tighten with a screw driver. If you insist on using the GM clamps, install the lower hose to the new radiator before installation.
Don’t forget to add at least 3 stop leak pellets (I crushed mine and poured them into the bottom hose) and it should take right at 2 gallons of 50/50 mix Dex-Cool coolant.
Run engine until warm, check for leaks and after cooled down (next day) check coolant level.
Automobile(s): 2002.5 F55 STS/65500mi, 2004 Ford F150 SuperCab4x4
MD Eastern Shore - Kent Island
Re: How to R & R ’99 Deville Radiator
GM discontinued their use back in 2003 - 2004 or so. If you have no nuisance weeps or had no leaks in the cooling system before whatever caused cooling system repair, there's no real sense in installing more goop in the system.
The tablets were installed to prevent nuisance weeps resulting in warranty comebacks, and for no other reason.
The tablets are Bar's Leaks #HDC and the equivalent powder is Bar's Leaks #G12BP.