So I have my 1941 truck down on the floor after a dakota clip swap. 318 Poly 727 setup. I have been checking into an IRS rear axle set up. I know people use the 90s Ferd Cougar Tbird stuff.
Any body tried to put a Charger IRS?? Not much info that I have found on line. What years??Any info would be a great help. Thanks

First thing I do when thinking along these lines is compare the track of each vehicle. If they differ can rim offset/width be used to adjust it. Then I wonder about how to hook the rear end to the transmission, what kind of driveshaft will I be looking at and how much will it cost me to get it made, if it can be made. Then I find a drawing of the donor's mounting points and see if they can be fitted to the recipient's chassis

A few more things I would want to look into, in addition to the track width mentioned above.:

Being able to somewhat match the brake systems size front to rear would be a consideration. The Charger is a much larger car (there for assumed as heavier), it may have much larger brakes then the Dakota has, where the Cougar/Thunderbird, being older may have smaller brakes more like those on the Dakota.

Then the future availability of component parts is the next concern. With the Ford stuff being 90s stuff, will replacement parts be available in 10 years? The Charger is still being built, we know those parts will be around for another 10-20 years.

The wheel bolt pattern could also be a concern. I am assuming you have the 5 bolt Dakota front hubs. They have an American bolt pattern. I don't know if the Ford of that age is still American or metric, but I know the Charger is Metric. The bolt patterns are close, but not a direct match. I'm nor sure I would want to run the wheels that has the same bolt pattern on both the American and the metric bolt patterns.

As far as mounting the components, as long as the track with is close, you may end up building a rear frame section to support the independent suspension, but once past fabricating the entire system, it wouldn't be much different then splicing the front clip. Track width can be adjusted with an independent rear suspension by shortening or lengthening the outer drive axles, of course limitations are involved, and the suspension travel at the upper and lower extremes would be effected.

Fabricating the entire new rear subframe is a pretty big (read that as a major) undertaking though. If a "kit" is available (read all reviews available), I would deeply suggest the "kit" could make life much easier, regardless of who's rear suspension system it uses.

Going to have to adjust control arm lengths as well if you need that much track change.

The Charger IRS is pretty self contained in it's subframe, except the upper spring and shock mounts. Maybe a set of coil overs would sort both out into one mount.

Sniper, your image didn't show up.

I haven't been under the rear of most any vehicle since the mid 1990s (after I opened my welding shop) except to do welding repair on something. That hasn't been much of an issue with the modern Chargers (I retired in 2019). Until the last few years, I haven't even seen under much of anything that has been on a hoist unless something needed to be welded. Then I was more looking at the area requiring the work.

that era cougar/t-bird had an odd 4 1/4" bolt pattern. was possibly metric, but that was a quick measurement.

Sniper that pix is very close to what the ford stuff looks like. Do you know what year that rear assy is from?? I was thinking of using coilovers just to make it easy.
To me it looks very doable..

They are all pretty much the same in regards to how they are bolted into the factory chassis.. I grabbed that pic off Ebay, says 2011 Charger RT.

Moparx there is a outer hub that can be changed to make it a 4 1/2 " bolt pattern on the ford stuff. Anybody by chance know the hib to hub measurements in the Charger rear axle?

The Charger specs say the rear track is 63.8" but the wheels are offset inward so the hub-to-hub is wider.

i didn't know that. what would that hub be from ?
if i were doing an IRS, i would probably use the challenger unit and modify the width to fit, just due to the added torque that unit was designed for over the ford unit.
but that's just me.

I believe this si the correct charger info. lug pattern 5x115, center bore 71.5mm,