As the proprietor of Geelong Differentials, Matt Dietrich has had a hand in some of Victoria’s toughest street and strip cars, and he’s had his fair share of personal projects along the way, too. His patina-clad F-truck was as cool as they come, but it wasn’t exactly a suitable family rig, so when kids came along, he had to let it go.

First published in the October 2026 issue of Street Machine

But while fixing to jam a V8 in the mini-tubbed HR Holden with which he replaced the Effie, Matt remained unable to shake his vision of a tough VF Valiant hardtop. When he finally stumbled across the perfect base vehicle for such a project, he couldn’t help himself. 

“I’m not really a Valiant person; I just like anything that’s cool,” Matt explains. “This one came up as a stock six-cylinder car in great condition, and it was just what I wanted. I was going to cruise it for a while as-is and start the project down the track, but the brakes were shot, so I ended up getting stuck in right away.”

Initial plans called for a tough little 318 between the front rails, but a chinwag with Garry Harrison at Modern Hemi Developments set the project on an entirely different path. “Garry reckoned a Gen 3 Hemi was the go,” says Matt. “He said a 318 would cost double the money, make half the horsepower, and wouldn’t drive as nice.”

Matt jumped straight on Marketplace and found a bloke who was selling an ex-Jeep 6.4-litre Hemi in Echuca. It’d shat a lifter, but as Matt planned on having the engine rebuilt and upgrading the cam and valvetrain anyway, it mattered not. Somewhat fortuitously, the seller was travelling to Geelong the following week anyway, so he was able to drop it to Matt’s door. How good!

Tony at TDR Engines treated the 392-cube new-age Hemi mill to a freshen-up, retaining the OEM crank and rods but fitting Mahle forged slugs, ported cylinder heads with oversized valves, and a Comp Cams 220/230 stick for some extra attitude and shove. The stock Jeep inlet manifold remains, but is fronted by a larger 102mm LS-style Aeroflow throttlebody. Managed by a Holley Terminator ECU and exhaling through a set of custom Exhaust Bros four-into-one headers, it’s handy for 400hp at the tyres – not too shabby!

Gen 3 Hemis are a good thing indeed, but we don’t see them transplanted into chrome-bumper muscle cars at the same rate as LS donks. So, Matt took to the Australian G3 Hemi Swaps page on Facebook to suss out how it’s done. “Andrew Dunnett up in Queensland sells a modified K-frame that works with an off-the-shelf Holley mid-mount sump,” says Matt. “The 727 trans bolts straight up with an off-the-shelf flexplate, and the Holley ECU runs everything, so it was a pretty straightforward swap, really.”

Matt had the cheat codes by starting with a car that was already neat and tidy from a body and paint perspective, so he didn’t get bogged down in what is often the most costly and time-consuming aspect of a build like this. “Having young kids now, I just don’t have much time to be building cars. Plus, I’m no good at panel and paint, so buying a car that had a good body, good paint and a good interior was the way to go for sure.”

That being said, getting the hardtop’s stance on point was a non-negotiable, which meant a worm-burning ride height and meaty rear hoops. “I wanted to tub the car as much as I could without touching the rails or the outer guards, because the car was already painted,” Matt explains. “We did a split tub job with 3.5 inches of width added to the stock tubs, and Adrian from SSD Performance sells a leaf spring relocation kit with traction bars, which gave us clearance for the 325/50R15s. It sits really nicely, but it’s still a very subtle-looking car.”

You’d be correct in assuming that Matt took care of the third member himself, opting for the ever-reliable nine-inch diff with a Truetrac centre, 35-spline axles and 4.11:1 gears. He went for Billet Specialties Street Lite wheels in 15x4in up front, and 15×10 on the rear with 3.5 inches of backspace for that cavernous rear dish.

As he alluded to already, Matt had to do precious little to the factory interior, save for adding a Holley 6.86-inch dash and B&M shifter. “All I did to the interior was fit an AP6 Val centre console, which fitted straight over the shifter and just made that look a bit more factory,” he says.

The VF hasn’t been finished for long, but Matt has wasted bugger-all time in getting it out and enjoying it with his wife Hannah and kids Frank and Abigail. And after crewing at Street Machine Drag Challenge on several occasions, he’s ready to get involved as a competitor. 

“I’m doing Drag Challenge in the car this year, and I can’t wait,” Matt grins. “I’ll be happy to run mid-11s, compete in DYO and just have some fun.”

We can’t wait to see him stick the hardtop in the beams at Victorian Motorsports Park later in the year! 

MATT DIETRICH
1969 VF VALIANT REGAL HARDTOP

THANKS
My wife Hannah and our kids Frank and Abigail; Ash Hodgson for helping with the tubs and fuel system; Greeny, Mick, Jem, Scotty and JB for helping in the shed, even if it was just drinking beers; Tony and Luke at TDR Engines; all the TAVOs who get upset when I call it a coupe and not a hardtop