* Axle type: Did your Bronco have Dana 44s front and rear, or a different combination? Different axles have different yoke sizes and lengths. This is the most critical factor.
* Wheelbase: The wheelbase (distance between the axles) affects the length of the driveshafts. Longer wheelbases need longer shafts. Broncos came in different wheelbases.
* Lift height: If you've lifted your Bronco, the stock driveshafts will likely be too short. You'll need longer shafts to accommodate the increased suspension travel.
* Transfer case: The type of transfer case (NP205, NP208, etc.) will influence the yoke size at the transmission end.
You cannot simply say "these drive shafts will fit." You must determine the specifics of your Bronco's axle configuration and then find driveshafts to match.
Here's how to find the right ones:
1. Identify your axles: Look for markings on the differential housings (usually stamped numbers). This will tell you if they are Dana 44s, 9-inch, etc. Pictures and online forums dedicated to classic Broncos can help in identifying them.
2. Measure your existing driveshafts: If you still have the original shafts (even if broken), carefully measure their length (center to center of the yokes) to get a baseline.
3. Determine your wheelbase: Measure the distance between the centers of your front and rear axles.
4. Check for lift kit: Note if you've added a lift kit and how much lift.
5. Consult a parts supplier specializing in classic Broncos or a driveshaft shop: Provide them with the axle identification numbers, wheelbase, lift height (if applicable), and transfer case type. They will be able to supply you with the correct length and yoke sizes.
6. Consider new vs. used: Used driveshafts are cheaper, but their condition is crucial. New driveshafts are more expensive but offer peace of mind and are usually balanced.
In short, don't guess. Take measurements and consult experts to ensure you get the correct driveshafts for your specific 1978 Ford Bronco. Using the wrong ones can lead to vibrations, binding, and even catastrophic failure.
