Clutch fitment question - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Canadian 72 C15 · 12-11-2025, 10:17 AM

I have a 72 GMC half ton with a small black 350 in it currently. Behind it is an SM 465 bull low transmission. I am swapping it out to an NV 3500 from a 2005 GMC half ton. I’m converting it to a hydraulic clutch and slave.

My question is will my pressure plate, clutch and flywheel work with the new transmission?

I have tested the clutch on the input shaft and it has the same spline as the SM 465. I have a 168 tooth flywheel which I know is compatible with an NV 3500. But I’m more so wondering about the pressure plate and the fingers whether they are any different for a hydraulic throwout bearing versus a mechanical fork which came originally on the truck.

Should I be able to just swap in the new transmission with the hydraulic slave and have everything work?

**70STOVEBOLT** · 12-18-2025, 12:35 PM

Are you using the original throwout bearing fork?

**57taskforce** · 12-18-2025, 01:44 PM

Can’t say for sure on the 3500, but I used a stock replacement 12” clutch for a 72 K20 when I converted mine to hydraulic using an 80’s aluminum truck bellhousing on my original sm 465.

**kwmech** · 12-21-2025, 01:41 PM

As long as you are using the diaphragm pressure plate and not the 3 finger, you'll be alright

12-11-2025, 10:17 AM	#1
Canadian 72 C15 Registered User Join Date: Oct 2020 Location: Hamilton Ontario Posts: 40	Clutch fitment question I have a 72 GMC half ton with a small black 350 in it currently. Behind it is an SM 465 bull low transmission. I am swapping it out to an NV 3500 from a 2005 GMC half ton. I’m converting it to a hydraulic clutch and slave. My question is will my pressure plate, clutch and flywheel work with the new transmission? I have tested the clutch on the input shaft and it has the same spline as the SM 465. I have a 168 tooth flywheel which I know is compatible with an NV 3500. But I’m more so wondering about the pressure plate and the fingers whether they are any different for a hydraulic throwout bearing versus a mechanical fork which came originally on the truck. Should I be able to just swap in the new transmission with the hydraulic slave and have everything work?

12-18-2025, 12:35 PM	#2
70STOVEBOLT Senior Member Join Date: Jun 2005 Location: Winona Lake, IN Posts: 7,062	Re: Clutch fitment question Are you using the original throwout bearing fork? __________________ 70 C/10 SWB 402/TH400/3.73 "The Needy Beast" 200,000 Mile Club Disc Brake Club Owner installed options: Front Sway Bar Power Steering Power Brakes Cigar Lighter Courtesy Lights Deluxe Side Markers Wiper Delay Sliding Rear Window Power Windows Power Locks Sniper EFI 2015 Silverado 1500 LS 4.3/6L80/3.23 lowered 2" front & rear

12-18-2025, 01:44 PM	#3
57taskforce All about them K’s Join Date: Jun 2014 Location: Land of Entrapment Posts: 6,975	Re: Clutch fitment question Can’t say for sure on the 3500, but I used a stock replacement 12” clutch for a 72 K20 when I converted mine to hydraulic using an 80’s aluminum truck bellhousing on my original sm 465. __________________ Tyler '57 3100 http://67-72chevytrucks.com/vboard/s...d.php?t=813888 '72 K20 Cheyenne: 5” lift, 35’s, front dana 60 blah blah blah… http://67-72chevytrucks.com/vboard/s...d.php?t=662879 ‘69 K10 SWB: 4” lift 33”s… in a million pieces http://67-72chevytrucks.com/vboard/s...d.php?t=805206 '98 Silverado LT K2500HD ECLB Vortec 454/4l80E: 6" lift 35x12.5x20’s

12-21-2025, 01:41 PM	#4
kwmech Senior Member Join Date: Mar 2003 Location: Colfax-California Posts: 8,941	Re: Clutch fitment question As long as you are using the diaphragm pressure plate and not the 3 finger, you'll be alright



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