PierreP Moderator note 2013-07-30 I am locking & archiving this old thread because:
1- The firmware download link is broken.

2-
...This is outdated and should not be used until the update due to the horrendous amount of bugs in it and instability (it uses an outdated and buggy set of some tools I made).
...this base pre-jailbroken firmware caused a mess of issues for people who used it 
*****
Original post:This is not Redd00r itself! It is a pre-jailbroken custom version of iOS 4.1.nor is it required to get Redd00r on an iPhone 3G it simply makes it easier to get Redd00r on your 3G, since it is prejailbroken.
Once installed, you must manually install Redd00r for iPhone 3G (see below).You will need to install the real Redd00r tweak on top of this once installed. This custom iOS 4.1 firmware is faster than Apple's/iTunes stock iOS 4.1.
***************PierreP edit: It will show as iOS
4.3.2 in > Settings > General > About > and elsewhere because it includes an iOS version faker.
Real iOS 4.3.2 cannot be installed on iPhone 3G as the most recent iOS it can handle is 4.2.1 and it will not enable you to run any iTunes apps that requires iOS 4.2.1 and up because the ARMv6 CPU of the 3G cannot understand the instructions sets of newer devices with the ARMv7 CPU and up. Sorry!
f0recast is a simple free standalone tool to instantly find essential iPhone info including Bootloader version and baseband. Works on Mac & Windows. Download the free f0recast & iREB tools here:
http://ih8sn0w.com/I just connected my iPhone 3G to my computer with iTunes closed, started the small standalone (means no install required) f0recast and it gave me all the essential info about the iPhone:

Soltmeal's pre-jaibroken iOS 4.1 works fine, I installed it myself on iPhone 3G that was running stock iTunes downloaded iOS 4.2.1 locked & jailed as a stepping stone to install easily Whited00r 6
Unlocked version because it is faster than iOS 4.1 + Redd00r IMO. After trying to install WD 6 on that stock in jail & AT&T carrier locked iOS 4.2.1, I was getting
iTunes error 1604. My successful workaround is:
1- Stock iOS 4.2.1 downloaded & installed by iTunes, disconnect the iPhone 3G from the computer while it was booting for the first time so not to be messed up by iTunes, reboot.
2- I used iREB on my Windows PC to put the iPhone 3G in DFU Mode then installed Soltmeal's pre-jaibroken iOS 4.1, disconnected iPhone from the computer, reboot.

3- Downloaded the Whited00r 6 Unlocked version, un-zipped it to get the .ipsw file inside, installed it like the WD tutorial says and disconnected the iPhone from the computer while it was booting for the first time so not to be messed up by iTunes and turned off and back on two times as recommended in the tutorial.
4- Turn off the iPhone 3G, insert my SIM, connect to iTunes and set it up as New as recommended in the
whited00r Tutorial - Installation
My iPhone 3G now runs smoothly & fluidly on Whited00r 6.
***************Download here: https://docs.google.com/file/d/0Byw5eHFZ4Fj6WFc0WngzU1Z4Rlk/edit?pli=1
This is a prejailbroken iOS 4.1 ipsw for iPhone 3G, making it easier to install Redd00r once it comes out (instead of having to jailbreak your device yourself), it is NOT REDD00R. Its pre-jailbroken and includes all the features of Whited00r 4.4.1. So instead of downloading normal iOS 4.2.1
(which is slower than this base) and jailbreaking it yourself, you can download and restore to this and be ahead of the game.
Here are some bonus features you get with this base which isn't in normal iOS 4.1:
GameCenter
Multitasking
Wallpaper
Cydia
plus some more stuff..
After Install, you must do the following to install Redd00r BETA (if you want it):1. Add the repo:
(click here to view the repo address)2. Install the package: Redd00r
3. After your device reboots, the setup app should open. Don't hit the home button if the screen is black (the app is loading)
4. Run through the setup app, choose your settings. Note it may take up to 10 MINS to configure your device IF YOU CHOOSE TO REMOVE RETINA IMAGES. It will take about 10 seconds if you don't.
5. Once you respiring, you are done! You can change your settings any time in settings.
PLEASE LOOK HERE for support on redd00r and more information (use this topic for firmware-related issues)
http://www.whited00r.com/forum/index.php?topic=6007.0This isn't hacktivated or unlocked. If you have an unlock, you need to manually hacktivate it.