Used BMW 4 Series Differential

The F32-generation BMW 4 Series ran from 2013 to 2020, with a facelift in 2017 that brought styling and electronics updates. For the differential specifically, the engine code and gearbox type matter far more than whether the car is pre- or post-facelift. That said, confirm with the breaker whether your exact registration sits across the 2017 boundary, as ancillary or mounting details can change mid-production without a clean cutover date.

A 2015 420d sits in the pre-facelift F32 generation and a 2018 420d sits in the post-facelift period, so you are crossing the 2017 facelift boundary. The engine code on both should be B47 (confirmed against your V5 or a VIN check), and fuel type and gearbox type also need to match — auto and manual units differ. Give the breaker your engine code, gearbox type, and registration so they can confirm whether the specific differential crosses that boundary cleanly.

Trim level alone does not determine differential fitment on the BMW 4 Series — the engine code, fuel type, and gearbox type are what matter mechanically. An SE and an M Sport running the same engine and gearbox combination will use compatible differentials, though an M Sport or M440i may carry different final-drive ratios, so always cross-check the engine code. You may find cosmetic differences such as different subframe covers or bracket finishes, so confirm the exact part number with the breaker against your registration.

No — rear-wheel-drive and xDrive models use fundamentally different drivetrain layouts, and the differentials are not interchangeable between the two. An xDrive 4 Series has both a front and rear differential as part of its all-wheel-drive system, whereas a standard rear-wheel-drive model has only a rear differential. Always tell the breaker whether your car is RWD or xDrive before requesting a quote.

The 435i and 428i use different engines (N55 and N20 respectively in the F32 generation), and differentials can carry different final-drive ratios tuned to each engine and gearbox pairing, so they are not straightforwardly interchangeable. Supply the breaker with your exact engine code from the V5 or a VIN check, your gearbox type, and your registration rather than relying on the badge alone. The engine code is the single most useful piece of information you can give a breaker for this type of mechanical part.

The F32 4 Series shares its platform with the F30 3 Series, and some drivetrain components do cross over between the two ranges. However, whether a specific differential unit is a direct swap depends on matching the engine code, gearbox type, final-drive ratio, and flange dimensions precisely. Route this comparison to the breaker with both sets of registration details or engine codes, as confirming exact compatibility across model lines is beyond a general guide.