LS Swap Your Classic Ford Truck or Bronco: Motor Mounts, Crossmembers & Transmission Mounts
The GM LS engine has become the default swap for classic truck owners, and for good reason: it is compact, light for its output, easy to find in salvage yards, and backed by a huge aftermarket. Dropping one into an old Ford F-Series or full-size Bronco gives you modern fuel injection, reliable power and parts you can find anywhere. The hard part isn’t the engine. It’s getting it to sit in the chassis correctly and stay there.
Autofab has been building engine conversion mounts since the early 1980s. Here’s what to plan for when you put an LS into a 1965–1996 Ford truck or Bronco, and which parts make the job a bolt-in instead of a cut-and-guess project.
Why an LS swap in a classic Ford?
- Power and reliability: a junkyard 5.3L or 6.0L usually makes more power than a tired original V8 and starts every time.
- Parts availability: LS engines, harnesses, accessories and tuning support are everywhere.
- Packaging: the LS is compact for a V8, so it fits in the Ford engine bay with room for headers and accessories when the mounts put it in the right spot.
Step 1: Get the engine position right
Where the engine sits sets up everything else: driveline angle, oil pan clearance over the crossmember or axle, header-to-frame clearance, and hood clearance. Universal weld-in mounts can work, but they make you work out that geometry yourself. Vehicle-specific conversion mounts take care of it for you.
1965–1979 Ford F-Series 2WD
Our FT-LS engine mount makes converting an early Ford F-Series truck to LS power a bolt-in job. One tip we get calls about all the time: most frames have two bottom holes and one smaller hole that help you line up the mounts, and two holes need to be drilled. The 1965 to 1967 frames don’t have the same holes, but you can usually find one to start from.
1980–1996 Ford F-Series and full-size Bronco
For the later bodies we offer a bolt-in mount kit. The passenger side bolts in like stock. On the driver side, you remove a few rivets from the stock frame bracket to install our mount.
On 4WD trucks and Broncos from 1980 on, pair the mounts with our LS crossmember so the transmission is properly supported:
Step 2: Don’t forget the transmission mount
Most LS swaps use a GM automatic such as the TH350, TH400, 700R4 or 4L60E/4L80E, and the stock Ford crossmember was never designed for those cases. We build transmission mounts specifically for GM transmissions in Ford trucks:
Building something custom?
If your chassis isn’t a stock Ford, or you’re building a buggy, race truck or a one-off, start with our universal plates. They’re mild steel and come with four T-103 tabs and two BA200 bushing assemblies. The tabs are only tacked in place, so you can move them to suit your design and still use Autofab’s proven mount design.
LS swap checklist
- Confirm your truck’s year, drivetrain (2WD/4WD) and cab/frame configuration.
- Choose vehicle-specific engine mounts, or universal plates for a custom build.
- Match the transmission mount to your GM transmission and crossmember.
- Check oil pan, header and hood clearance before final welding or drilling.
- Check driveline angle and driveshaft length once the engine and transmission are in place.
Talk to the people who build the parts
Every truck is a little different, and decades of hard use make it more so. If you aren’t sure which mount fits your build, contact the Autofab team. We design, build and test our parts in Southern California and are happy to help you get the swap right the first time. Browse all Ford motor mounts or shop the full catalog.