66-77 Bronco 3.5″ T-Rex Performance Package

For this performance package we have 2 different travel options. You can stay with the factory front shock tower that uses a stud eye shock or you may opt to go with our long travel option and install a new set of bolt-on shock towers and longer shocks to increase your articulation.

If you already have some type of aftermarket shock hoop or you are dealing with rust issues, we suggest going with the "Mid Travel" option so that you can start with a bare frame rail and install our new shock towers and pair it with the correct shock.

Choose System - Midnight Black or Duff Signature Blue. You can also choose between the two shocks we offer for this package. The classic white Duff 70/30 or the modern black MS2020 Shock.

Not sure what shock is right for you. Learn more by watching this video.

This section contains all the main lift system components except steering and your leaf spring configuration. Those will be chosen in the next sections.

This system includes the following; 3.5" coil springs, upper coil retainer tabs, Spring Eye and Shackle Bushings, 7 Degree C-Bushings, Frame to axle Lines, Spring Eye and Shackle Bolts, HD U-Bolt Plates, T-Rex Radius Arms, Dual Sport Front Sway Bar, Hellwig Rear Sway Bar, Dual Sport Lower Coil Retainers, Front Sway Bar Quick Disconnects, Front Sway Bar Brackets, Rear Sway Bar Quick Disconnect.

There are additional accessories available to further customize this system such as a body lift, c-caps, and parking brake cables, those are presented in the final steps.

You will need to select the proper knuckle mounting hardware for the steering linkage that comes with this system. If you are not sure which one you need or not sure if your Bronco's knuckles are stock or have been modified then you will need to verify that before choosing.

If you are looking for the strongest or off-road options for your setup then you will want to choose the 3/4" bolt or the F150/GM 1-ton mounting kit options. Both of these options may require drilling/reaming and we provide those tools as an add-on once you make your selection.

564X - 3/4" Bolts for TRO or TRU applications - Requires Drilling of knuckles
5660 - Tapered Stud Kit for Stock Early Bronco Knuckles Tie Rod Over Applications
5661 - Tapered Stud Kit for F-150 / 78-79 Bronco & GM 1-TON Tie Rod Over Applications

Before you choose your spring, you need to understand the difference between Medium duty and Heavy duty. First off the difference has nothing to do with ride quality. Our Heavy Duty spring will not give your Bronco a stiffer ride. This is simply to make sure your Bronco will sit level or at the very least not squat in the back when your Bronco is complete.

Medium-Duty springs are for 66-77 Broncos that have very few add-ons or accessories in the rear. For example, if you have a stock half cab or roadster you would choose medium duty. If you have a resto-mod wagon with a soft top, stock rear bumper, no spare tire, and stock fuel tank, with or without a back seat but not typically using it, then you also would choose medium-duty springs. We do NOT recommend medium duty for trailer towing.

Heavy-Duty springs are for 66-77 Broncos that are geared more towards a well-equipped resto-mod for on and off-road use. If you have or plan on upgrading to a 20+ gallon rear fuel tank, tire carrier + tire, steel plate rear bumper, and/or want to run a hardtop, the heavy-duty leaf spring is also a great choice for your build. These are also the best option if you plan on ever towing anything with the Bronco. If you like going off-road and hitting the trails, the heavy-duty leaf springs are typically the best option for you as well.

For some of you, there will be some combination of parts that accessorize your Bronco in between a soft, medium, heavy, and extra heavy-duty setup. This is why we offer lifted spring perches, 1/2" and 1" lift blocks as well as pinion shims for driveshaft angle corrections to get your ride height and driveability spot on. Our new 1/2" lift block will also offer the option to move the axle back for that perfect amount of tire to fender clearance for the uncut lifted 66-77 Broncos.

Installation Note: The Double spring Wrap aka Military wrap is to be installed towards the front of the vehicle.

You can also add on great upgrades when purchasing these springs like Leaf spring and shackle mounting hardware, Shackle bushings, the Duff HD spring plates, U bolts or HD U- bolts (both that come standard with new HD hardware), HD shackles, pinion shims, lift blocks and new Duff HD weld on spring perches offered in factory and 1" built-in lift.

We highly recommend you consider adding this to your purchase now. This anti-rear axle spring wrap device prevents damage and failure to your rear driveshaft and leaf springs. This is a must for anyone who has a heavy foot, running 300+ horsepower, has a manual transmission and/or likes to go on and off road with their Bronco. Customers have stated the Torque Tamer has also made their Broncos more stable off road and smoothed out their take offs and shifts.

Important: when installing the Torque tamer to have your driveshaft angles dialed in with 2-4 degrees of difference in pinion to driveshaft angle. This typically will require pinion shims and they are offered in Body lift & Accessories for this kit. You can also weld on HD leaf spring perches offered here.

Note: If you are not running one of our exhaust systems this product may require you to modify the exhaust system you are currently running. We highly recommend you use one of our exhaust systems as they work with all of our parts. More info here

You will be presented with 2 options below - 1) Our Heavy Duty Torque Tamer for OEM frame 2) Our DIY HD Torque Tamer for Aftermarket Frames

NOTE: crossmember in our DIY is NOT powder coated or fully welded. For more info click here.