Z32 300ZX VG30DETT Gearbox Conversion Kit


R33 / R34 Skyline RB25DET Gearbox Conversion Kit

>>> into the Nissan Silvia / 200sx / 180sx / 240sx with the SR20 engine <<<

Pretty much everything between the two gearbox conversions are the same; both use Australian made 1-piece full-face thick CNC machine billet alloy adapter plates, both uses 3-piece multi-adjustable CNC machine billet cross members, both are engineered for the S13/S14 chassis and both have a kit engineered specifically for the S15 (you can thank the owner of Alpha Omega for owning an S15 and wanting an S15-specific kit), both gearboxes in the same years are the same internally so same gears, same synchros, same strength, we’ve made it so that both Z32GCK and the R33GCK-Factory will fit single, twin, triple and quad plate clutches, the output shafts are the same…

… the tangible difference is in the shifter setup, and the knock on effect of the entire conversion.


10 years of Z32 gearbox conversions and there have been absolutely zero failures to date. None whatsoever. We are extremely proud! =)
The only real complaint of the Z32 Gearbox Conversion Kit is the shifter. When using the Z32 gearbox there was this seesaw conundrum:

  • Pleasant shifter position = unpleasant shifter feel + no need to cut metal
  • Unpleasant shifter position = pleasant shifter feel + cut metal

We chose to have the pleasant shifter position and NOT cut metal by moving the factory shifter set up. Feedback from many customers say it takes a week or two to get used to the new shifter feel and many like the way you can slam the 1st to 2nd gear change whilst disliking the 4th to 5th change. But some people just don’t like it full stop. Fair enough. No argument here. For those people you can have the pleasant shifter feel by using the standard Z32 shifter set up – just bear in mind that the shifter will sit 60mm (~2.5″) too far back, you’ll have to cut metal out of the chassis, have a huge gaping hole where the shifter is meant to be, and you’ll need to dog leg the shifter.

BTW dog legging also produces an unpleasant shifting feel too where the gearknob moves significantly in the Z-axis.

Z32GCK installed in an S13: The shifter position isn’t factory perfect, but still fits better than any Z32 conversion out there


We introduce the Alpha Omega Racing “R33GCK-Factory”.

A working prototype was displayed at the 2017 Yokohama World Time Attack Challenge. We’ve spent literally hundreds of hours of engineering to get it to the WTAC 2017 and continued for many more hours after the event to achieve perfection. The finished product is our most elegant solution and our greatest achievement to date. We launched it at the 2018 Yokohama World Time Attack Challenge and yes that means we refined the working prototype for 12 entire months… that’s over 20 months of total development work.

Fully functional R33GCK-Factory prototype at the 2017 Yokohama World Time Attack Challenge

The R33GCK-Factory’s shifter is positioned perfectly in the centre of the Nissan Silvia S13/S14/S15 shifter hole and it moves in the perfect way with a perfect shifting feel. No compromises. We’ve also incorporated a 17.5% shorter-throw using the OEM standard shifter! 15% was pretty okay and 20% was a little too much.

  • No dog leg shifter
  • No gaping holes
  • No metal cutting or bashing
  • No plastic cutting or shaving
  • Perfect shifter position
  • Perfect shifter feel
  • All functions work perfectly including reverse lockout, reverse sensor, and neutral sensor
  • Built-in 17.5% short-throw action using the OEM standard Skyline shifter
  • All the standard interior trim fits like factory

R33GCK-Factory installed: perfect shifter position


Sooooooooooooooooooo if the R33GCK-Factory is all singing all dancing perfection then why would I ever want to buy the Z32GCK?


There are more parts in the R33GCK-Factory and not ‘just’ more parts but the parts are excruciatingly more complicated to engineer and manufacture – probably why nobody has ever done it before. Since the shifter feel was the biggest complaint of the Z32GCK we selected expensive high-carbon stiff AF billet steel for an impeccable shifter feel, but stiff AF high-carbon steel wears out tooling and the CNC machining is a slower process and that drives up the cost. Don’t forget that R33 RB25DET gearboxes are always in high demand – every rear wheel drive RB-engined and RB-swapped car wants this gearbox and that makes it the third reason why the cost is higher than the Z32GCK. The forth reason is that the installation will be more expensive; there are more blind holes in the Skyline bellhousing to modify and both gearbox casing needs to be removed and re-sealed in order to install the conversion parts.

Depending on how hard you shop and how much you can DIY, you can save over two thousand dollars (Australian dollars) by using the Z32GCK. So that you can budget and decide for yourself, we’ll continue manufacturing both Z32 and R33/R34 gearbox conversion kits.

Whilst I have your attention let me just quickly touch on the Z33 / 350Z / Z34 / 370Z 6-speed gearbox conversion VS the 5-speed Z32 / R33 / R34 conversion.

Yes, 6 gears are motherfu*ken awesome! But we’re of the opinion the multiple conversion problems of the Z33/Z34 gearbox into a Nissan Silvia chassis far outweighs the advantage of one extra gear. The other MASSIVE problem is that there is no support or upgrades – you’ll be stuck with no room to move. On the other hand the Z32 / R33 / R34 is a great base to start from, these gearboxes gives you lots and lots of options from budget to baller upgrades: 3 gear upgrades, 5 gear upgrades, assorted gear ratios, upgraded helical gears, straight cut gears, upgraded input and output shafts, upgraded sandwich plates, billet selectors, synchromesh engagement, dog engagement, clutchless shifting and now even a 6-speed sequential gearset that will drop straight into the Z32 / R33 / R34 housing. Wait. Holy sh*t! That means we can now have a no compromise perfect fitting + perfect shifting + perfect angles 6speed sequential in your Silvia! Who’s going to be the first?!

R33GCK-Factory – production ready – at the 2018 Yokohama World Time Attack Challenge




Everything is engineered and designed to work together so we can guarantee the quality and fitment and give aftersales support. To that we hear people say something like “Bullsh*t mate the shifter doesn’t affect anything else you just being a gronk etc”

Guess what? We have sold bits and pieces separately in the past. We’ve been specialising in Nissan Silvia gearbox conversions for over a decade – let me repeat that – 10 years dedicated to gearboxes on one car. I hope it isn’t too farfetched to claim we’ve seen a few things during our time. Cut and shut bellhousings, thin uneven and flimsy adapter plates, alignment dowels out of place or even totally omitted WTF!, 4 bolts holding the gearbox on, cross members lowering the gearbox below the centre of the earth so that they can say “look mum you don’t have to cut the chassis!!!” and so on. All of these non-shifter related parts have affected the shifter feel, selecting gears (more like not selecting gears) and the shifter position.

If you’re lucky you can find the seller of those other parts and you will hear “nah mate not my problem it’s because of bla bla bla”, then we get a call from the customer yelling and swearing at us because so and so said such and such, and nobody ends up happy. We don’t need that in our lives and neither do you.

Alpha Omega Racing engineers and manufactures “full kits” so that your S-Chassis lives a long, reliable, high-performance life. “Engineering The Limit”. That’s what we stand for.

A reliable Silvia? Imagine that.

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