I dont have info much info on what it came from, just 2000 model year, LSD rear.
if they turn the diff by hand, can the difference between 3.9, 4.1 and 4.3 can be easily seen?

If it's a NA6 you'll need a drive shaft too.

I got a 1.8 open diff for $450 ( with axels and drive shaft ) but I had to drive almost three hours to pick up.

Turn input shaft until wheels rotate once, count how many turns the input needed to do that.
Pro: easy, fast.
Con: not totally accurate, can be hard to tell a 4.1 from a 4.3


Crack casing open, count teeth on crown, count teeth on pinion, divide crown by pinion
Pro: 100% accurate, also lets you confirm if it's an LSD while it's open
Con: you've got to pull the diff open to do it.

Any idea if the chassis number have that info attached like our VINs do?

I gave the Mazda dealer my Vin and they couldn't tell me...

AFAIK if it has power windows and leather interior, it had a torsen from the factory.

That is assuming it was from a 6-speed manual transmission car.

.....and that assuming its from the US. All or nearly all NB's in Europe came with a 4.1 diff on 5 speeds and 3.6 or 3.9 for all 6-speeds. Afaik that's also true for the many JDM NB imports driving around in the UK. We have a very hard time hunting down 4.3 ratio 1.8 diffs here because the only source is a semi-rare JDM NA8 R-package equivalent.

The only info I have is that its from a year 2000 JDM Miata.
If you call the 800 Mazda number, and give them a VIN they will tell you everything about that car. Ive been running all the local junkyard miata vins, so far everything has been auto, or 3.9. I asked the eBay seller for more info, maybe they have records of the Chassis Number that Japan uses to ID their cars.

I see a guy selling a 4.1 for $750 about 2 hours away
Found a guy selling a 1.6 LSD kit for $400
Another 1.8 4.3 core only for $750
A 4.3 Fuji set for $600

$750 for a torsen is pretty good.

The Fuji is still a LSD so that's not bad either I think.

(Make sure they come with axels and DS)

The fuji is noticeably worse in terms of power transfer. Also has that whole breaking tabs problem.

It's better than an open but I wouldn't swap one in if a torsen is available. I just swapped the tf from my 03 a few weeks ago to a torsen and it's a nice upgrade.

You can look up spec sheets.

But remember you're buying from a car that's 14 to 30 years old, so there's no guarantee that it's the same diff it left the factory with.

Should probably add.

If you're buying a Torsen, grab a T2.
Stronger since the helicals are mostly enclosed within a cast housing.

Compared to the T1 where they're held in with much less material, which can, and does, break.

(Not that i've ever broken one, but my diff builder showed me his box of busted T1s, and said he's never had a busted T2 come back)

the JDM seller had a 3.9 diff. junkyards had a 4.3, but it was stripped the day it arrived. and they wanted $800 just for the diff.

Man, i didnt think it would be so hard finding a diff for a Miata.

This guy seems to have many diffs: https://chicago.craigslist.org/nch/p...009992620.html

There's also this guy, but its a 4.10 https://chicago.craigslist.org/nch/p...009992450.html

You might just have to pay to play if you really want a 4.30

I cant find a single 4.3. already looked over all the craiglist ads from my area, and surroundings. those two ads are from the same person and he wants $900 for the 4.1 swap
some dude in florida might have a 4.3 set for $1300 + shipping
ebay i see stuff go for $1100+300 shipping or not willing ton ship

Well, one of the UK breakers has VLSDs for $265 shipped if you just wanna get rolling again.

Have you tried looking in Canada? Exchange rate difference would be worth it for you. Most torsens I see here go for 800 to 1000 cad which is around 700 usd.

$800 for a diff doesnt sound too crazy to me.

I paid $1100au (~$760usd) for my 4.1 T2 about 8 years ago. (granted, as a full unit ready to bolt it)
And that was here in Australia, where the 4.1 is dirt cheap since every NB1 came with them.


Any reason you really want a 4.3 instead of a 4.1?
it's only 5% shorter, so it's not going to be a night and day difference (hell, if you need the shorter gearing just get lower profile tyres for the little bit extra)