* Truck configuration: Regular cab, extended cab, crew cab, different wheelbases all affect driveshaft length.
* Engine and transmission: Different combinations will change the drivetrain geometry and therefore the driveshaft length.
* Rear axle ratio: While less impactful than the other factors, this can slightly alter the length.
* Lift kit or lowered suspension: Any modification to the ride height will significantly change driveshaft length.
To find the correct length, you must measure the driveshaft itself or consult a parts catalog using your truck's VIN number. A parts store or online retailer specializing in classic Ford trucks will be able to help you find the correct driveshaft for your specific 1986 F-150. Providing them with your VIN is the best way to ensure a proper fit.
