Welded diff or LSD?
Answer four questions and get a straight recommendation with the reasoning, rather than another "it depends".
Why this is the first real decision in a build
A factory open or viscous differential sends power to whichever rear wheel has least grip. In a drift that is the unloaded inside wheel, so it spins, the outside wheel does nothing useful, and the car will not hold a line no matter what else you have bought. Getting both rear wheels turning together is the one modification that turns a rear-wheel-drive car into a drift car, which is why it sits ahead of suspension, angle and power in the build order.
What the recommendation is weighing
Whether the car is also your transport. The biggest practical difference between the two options. A welded differential chirps and skips the inside tire at parking speeds, wears street rear tires faster and is harder work in the wet. None of that is dangerous; all of it is daily.
Your power target. A locked differential transmits every shock load straight into the axles, the driveshaft and the differential mount. An LSD has some compliance, which is why it becomes the kinder option as power goes up - and why the phase 3 drivetrain reinforcement item exists for cars running welded at real power.
Your budget for this one part. Published figures put welding at $100 to $300 at a shop and a used clutch-type LSD at $400 to $800. That is a four-to-eight-times gap for a part that does the same essential job, so on a tight budget welding is not a compromise - it is the answer, and the saving becomes rear tires and event entries.
How long you will keep the car. Welding is permanent and an LSD can be rebuilt and sold on, so a long-term car tilts toward the LSD and a car you will own for a season or two tilts the other way.
What it deliberately does not ask
Which chassis you have, because the answer is substantially the same across everything we cover. What does vary by chassis is availability: used clutch LSDs are plentiful for the S-chassis and findable but less common for an AE86 or an IS300, and some cars - the GT86 and many 350Zs - came with a factory limited-slip differential already, which means this decision may already be made for you. Check before you buy anything by driving slowly in a tight circle on full lock and feeling for both wheels driving.
One thing to do either way
Fresh differential oil, and check the differential mount. A locked diff loads that mount in a way the factory never intended, and on several chassis - the S-chassis in particular - the mount area is also a known rust spot, so the two problems compound.
Questions
Which is better for drifting, welded or LSD?
Both work. A welded diff is completely predictable and costs $100-300; a clutch-type LSD is quieter, smoother, kinder to the drivetrain and costs $400-800 used. The deciding factor for most people is whether the car is also their transport.
Will a welded diff damage my car?
It is harder on the axles, driveshaft and differential mount than an LSD because every shock load goes straight through. On a stock-power car that is rarely a problem; once you add real power it is why the drivetrain reinforcement item exists.
Is a new LSD worth it?
For a competition car running long sessions, yes - known condition, rebuildable, adjustable. At $1,100-2,200 it is more than most first builds’ entire phase 1, and it will not make you faster while you are learning.
How we make money, plainly. Some parts links earn us a commission. Parts with no affiliate option are still listed, with a plain link, so the plan is never shaped by what pays us. We do not take payment for placement, and the budget pick is labelled as the budget pick even when the expensive one pays more. Full disclosure.