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This thread hopefully will be the place to compile all the info for performance and replacement parts for Borg Warner, Dana/Spicer diffs etc..

I'll start with a list of performance LSD centers for the M75/M76 and M78 BW diffs from various good manufactures.

Eaton Truetrac PN: 99-TTRC9837-00 (type: torque biasing) 28 spline, suits M78 but listed some places as fitting M75, 76 and 78
Torsen Traction PN: 409200-0305E (type: torque biasing) 28 spline, M75, M76 (3.23 and up ratios only) for 3.08 and lower PN:409160-9032
Quaife PN: QDH3M (type: torque biasing) 28 spline, M75, M76
Kaaz PN: DAG3820 (type: multi plate clutch, 2 way action ) 28 spline, M75, M76, M78 ( pinion in M75 and 76 needs machining for clearance)


Feel free to add part numbers and other info and I can add it to the first page.

Good idea for a thread. Can I make 1 suggestion? if you have information that you got from other sites please add links, especially for parts suppliers that are good to deal with (price, quality of service, etc.).

Just google the part number is the best way as each manufacture have a different distribution scheme.

Kaaz Japan doesn't even have a site in my searching and the US site lists nothing (0 manufacture support seems to be the rep), Trutrac was hit and miss, only retail listings as with Kaaz, Quaife was via email and actually looking at technical drawings, measuring etc..., Torsen is listed on their site.

Shouldn't that be a Harrop Truetrac? Eaton only do one for the M80 (to suit Commodore diffs).

For the NZ Guys that are based in the upper North Island, I use this guy http://www.trademe.co.nz/Members/Listin ... ipping=all but I recommend contacting him directly as he'll do better prices (no trademe fees etc). He's based in Hamilton

He Can supply gears, centers and bearing kits for the M80 as well as the M75/76/78 as well as the other major makes/brands etc.

Harrop only came up as VZ, VE etc diffs when I search. Harrop and eaton are partnered anyway as far as I understand so I don't think t matters what you call it, Harrop is just an aussie engineering company that use Eaton's services to make some of the products to suit our market. Eaton does the actual manufacturing and owns the Trutrac technology as seen here. http://www.eaton.com/Eaton/ProductsServ ... /index.htm

vlad01 wrote:Harrop only came up as VZ, VE etc diffs when I search. Harrop and eaton are partnered anyway as far as I understand so I don't think t matters what you call it, Harrop is just an aussie engineering company that use Eaton's services to make some of he products to suit our market. Eaton does the actual manufacturing and owns the Trutrac technology as seen here. http://www.eaton.com/Eaton/ProductsServ ... /index.htm

Not quiet. Truetrac is from Eaton. Harrop make em under license to suit our diffs but they are a better quality and can handle more power.
This is an Harrop M78 next to Eaton M80 Truetrac. The Harrop is manufactured from better quality materials but I believe the worm gears are original Eaton.

Interesting? I didn't find anything under the Harrop name for M75 or M76 though, only as the Eaton one. So it looks to me you can only get Harrop for the latter models of holden.

Harrop Truetrac M78 http://www.trademe.co.nz/Members/Listin ... ipping=all

Harrop Truetrac M80 https://www.harrop.com.au/shop/automoti ... line-eaton

They also do the above centres in 31 spline.

The listing for the M78 above lists models VL-VT series 1.......

The above Harrop M80 True Trac is different to the Eaton M80 centre. I'll link it later (gotta take the boss out for dinner).

The M75 and M78 (presumably also M76) centres are interchangeable, its only the gears that differ. So any centre that fits one will fit the other (if you're looking for a Commodore LSD centre buy one from a later model Falcon, cheaper and less wear).

My understanding is that Eaton do not make a Truetrac to fit the M75 (etc), so Harrop takes Eaton internals and manufactures a housing to the slightly different dimensions. Not sure about the improved quality thing, sounds like marketing hype to justify being double the price (sad but makes sense when you consider you are basically paying for the Eaton then paying Harrop for a whole new housing on top).

Note that if you are considering fitting one of these units you may have clearance issues to the end of the pinion gear with gearsets 3.45+ which require machining. They talk about trimming the unit itself but I didn't want to void the warranty on a $1500 item (not to mention it seemed like a bad idea) so I ground a small amount off the end of the pinion itself


(don't mind my fancy tool post grinder)

As I know it, the Holden M75 LSD centers don't have the groove machined inside the spider side gears to retain the stub shaft as used in the IRS diffs. This is where I believe the M76 came comes from as I believe it signifies the IRS centers.

Having seen the Harrop and Eaton units side by side I'd have to say the Harrop looks to be off better quality. Eaton rate their unit at 500hp, Harrop rate theirs higher at 500kw.

How much did you end up taking off the face of the pinion?