Frequently asked Questions  - FAQ's - for the TruckIRS Installation kit

What is the price of the truck IRS Adapter Brackets?
$395 plus shipping… US Postal shipping is $30 in the continental US. UPS shipping costs run between $25 and $60 in the Continental US… but we ship worldwide. UPS shipping is based on a 25 lb box shipped from zip code 32931 

How do I pay for a set of truck IRS Brackets?
We accept Personal Checks, Cashier's Checks and Money Orders. Please make checks payable to: Team321 LLC and send check to: Dave Held 750 N Atlantic Ave #501  Cocoa Beach FL 32931

We also accept payPal - payment can be made to

I would like a set of brackets for my car or truck, but it's not a 1948-79 Ford. How can I get IRS Adapter Brackets for my vehicle?
We can make brackets to adapt the T-bird / Cougar / Lincoln Mark 8 IRS subassembly to a wide variety of cars and trucks. For a full explanation, send and email to and we can provide you with the details.

What size wheels / tires can I use with the truckIRS rear suspension kit?
Based on the photos on installation procedure... There is about 2" between the inside of the tire and the outside of the truck's bed... this is shown with the fender removed... so to be safe, I wouldn't to any closer than 1.5"

Further down... with the fender installed, there is about 1 1/2" of clearance between the outside of the tire and the fender lip... so let's call it 1" to be safe.
Having said / seen that, I conclude that you can use a tire that is 2.5" wider than the factory lincoln mark 8 tire with the same wheel offset... Lincoln used a 38-40mm offset rim and a 225/60-16 tire.

225mm + 2.5" = 8.86 + 2.5 = 11.36 inches = 288.5mm
so a 275 width tire will fit the rear.

What is the track width of the T bird / Lincoln rear suspension?
I measured the hub - to - hub distance on a Lincoln IRS and found it to be – 63 1/4"

I also measured a T bird rear suspension with tires / wheels installed - The Outside / Outside tire measurement is about 66 1/2" ( using the factory T bird wheels / tires ).

The spec'd track width of the Lincoln Mark  8 is 1,529mm or 60.19" - but track width is a funny thing - since it is a measurement from the center to center of the tire... which is only useful if you have the tire and wheel ( especially offset ) info... which is usually not given... The only offset info I can find online indicates it is 38 - 40mm. With this in mind, the calculated hub-to-hub measurement is 63.25" which compares favorably with my measurement.

What type of truck does the IRS adapters work on?
The IRS adapter kit has been proven to work on Ford Trucks ranging from 1949 - 1979,  1955 - 1959 Chevy Trucks and  Ford Ranger trucks.

My truck is not a 1949 - 1979 Ford truck, but I want to install your kit... How can I tell if it will fit my truck?
I am working on a kit for 1997 - 2003 Ford trucks. If you tell me the dimensions of the frame rails as measured just above the rear axle - the inside-to-inside AND outside-to-outside ( in inches ) I can quickly tell you if the adapters and IRS unit will fit your truck ( or car ).

What is the best car to get the IRS out of?
That depends on what you mean by the best... Any 1989- 1997 Thunderbird or 1993 - 1998 Lincoln Mark 8 has an IRS that will work with these adapters. All Lincolns feature an Aluminum Differential - which looks better and is lighter than the cast iron piece found in the T-birds. Some T-birds have rear disc brakes, some have drum brakes... all Lincolns have rear disc brakes. It is best to get an IRS out of a V8 powered car since the axles are stronger than the V6 axles.
Lincolns have air bags that may or may not be used with an aftermarket airbag compressor / controls / etc...
The Lincoln air bags can be replaced with coil springs, or aftermarket airbags.

If you prefer coil springs to air bags, look for a V8 Ford Thunderbird with rear disk brakes. If you would like to use aftermarket airbags, get a Lincoln Mark 8 and I can recommend airbags and provide all other pieces you need. 

What is the bolt pattern of the Tbird / Lincoln rear hubs? 
5 on 4.25"  (or 5 on 108mm)  is the original bolt pattern. 

I would like to use the standard 5 on 4 1/2" Ford bolt pattern - can I do that?
Yes, that can be done... send an email to  for information on changing the hub to 4 1/2" bolt pattern. 

I cannot weld... but I'd like to install this IRS... Do you offer a bolt-in unit?
Currently we do not, but the welding associated with installation is straightforward, and if you do some looking around your area, you are likely to find someone who can do the welding. If you cannot - contact us and I may be able to refer you to someone in your area to do the welding for you.

How long should the installation take?
The total install time will vary with the experience / expertise of whoever is doing the job... but on average it will take 2 - 4 hours. The vast majority of the time will be spent measuring the wheelbase, alignment, etc... prior to welding the adapters to the frame. This procedure can be done on any flat, level surface - but it is time-consuming. This time estimate assumes the truck bed and the original rear end has been removed.

Will the truck bed fit on top of the new IRS once it's installed?
Yes, the new IRS does not interfere with the frame nor does it interfere with the bed.

The IRS adapter kit costs $395 plus shipping... but what is the total cost of all components to do the job?
Right, the adapter kit from Team321 LLC costs $395
The IRS from your favorite wrecking yard costs anywhere from $150 - $300
Depending on the existing driveshaft / rear end in your truck, you may have to change the driveshaft flange.

Can I use the factory T-bird coil springs?
You have the option of using the factory coil springs - but they must be cut ( shortened ) in order to fit. Typically 1/2  to 1 1/2 coils must be cut. When cutting springs, only cut 1/2 coil at a time. Cut 1/2 coil, reinstall the springs and see if the ride height is where you want it. If you want it lowered, cut another 1/2 coil.
Another option is to use sport springs that are designed to lower the T bird's ride height.  I do not have a current vendor for lowering springs, but if you find one - please let me know.

What about air springs? If I use a Thunderbird IRS unit originally equipped with coil springs, can I add airsprings?
Yes, Team321 has airspring adapter brackets and can recommend the correct airsprings for your application.

What about the front suspension? Do you make a kit for the front as well?
We have installation kits to mount a 2003 -2011 Crown Victoria (Crown Vic) front suspension in Ford Trucks. Click HERE for more details on installing a Crown Vic front suspension.

What other products does Team321 make?
We manufacture a 62" track width front suspension based on Crown Vic control arms and spindles,custom tubular Rear Suspensions - including mid-engine applications. Team321 also has talent, tools and machines for a variety of 2D and 3D CAD design and fabrication.

I see that Team321 makes a tubular IRS unit - will this unit fit my truck?
Yes,  Team321 makes a custom, tubular Independent Rear Suspension for cars, classic trucks and other custom vehicles. All we need is frame dimensions and we design and IRS to fit your truck or any other vehicle. We also design and manufacture rear subframes.

The reason for coming out with this adapter package for utilizing the T-bird / Lincoln IRS, was to offer a low-price option for improved Rear Suspension.