Automatic Transmission Questions - The 1947 - Present Chevrolet & GMC Truck Message Board Network

BLACK AND BLUE 67-72 · 07-07-2002, 05:41 PM

I was wondering if anyone knows if a 400 Turbo bolts up the same as a 350. And are the overall lengths the same? I don't want to have to have my driveshaft cut. Also which length tailshaft long or short came in a truck? And why are the 400 Turbos a stronger transmission than the 350's? Please help!!!

68 with 350 TPI · 07-07-2002, 05:50 PM

The 350/400 will interchange on the bolt up just fine.
That is so long as it is a Chevy pattern and not a BOP (buick,pontaic,olds) .

Also make sure if it is a long or short tailshaft to have an exact fit.

The 400 is stronger mainly because of the drum/sprag has more holding power.

The 350's drum is smaller and with less rollers in the sprag.

But the 400 will use a little more HP to run. about 10-25 hp depending on what is done to it, and wear and tear.

Sinister · 07-07-2002, 11:01 PM

long tail shaft if you have 2 wheel drive...
the drive shaft is different for a 400...
check out...
[url]http://my.en.com/~thall/olds/oftrn.htm[url/]

Longhorn Man · 07-08-2002, 12:07 AM

The 400 has a longer overall length too. You'll have to move your cross member back, shorten your shaft, and get a new yolk. Over an inch longer than the TH350 short shaft that was origianl in our trucks.
I'd just find a TH350 IMO.

BLACK AND BLUE 67-72 · 07-08-2002, 11:11 AM

Thanks Guys!!!

07-07-2002, 05:41 PM	#1
BLACK AND BLUE 67-72 Firefighter Join Date: Feb 2001 Location: Yellville, Ar, USA Posts: 1,943	Automatic Transmission Questions I was wondering if anyone knows if a 400 Turbo bolts up the same as a 350. And are the overall lengths the same? I don't want to have to have my driveshaft cut. Also which length tailshaft long or short came in a truck? And why are the 400 Turbos a stronger transmission than the 350's? Please help!!! __________________ '72 Chevy SWB 350 Auto '67 GMC LWB 350 4 speed '70 Chevy 4x4 Stepside 350 Auto Yellville, Ar. USA

07-07-2002, 05:50 PM	#2
68 with 350 TPI Registered User Join Date: May 2002 Location: Wingate NC Posts: 456	The 350/400 will interchange on the bolt up just fine. That is so long as it is a Chevy pattern and not a BOP (buick,pontaic,olds) . Also make sure if it is a long or short tailshaft to have an exact fit. The 400 is stronger mainly because of the drum/sprag has more holding power. The 350's drum is smaller and with less rollers in the sprag. But the 400 will use a little more HP to run. about 10-25 hp depending on what is done to it, and wear and tear. __________________ Life is good with a 6-71 supercharged 355 in a 72 camaro

07-07-2002, 11:01 PM	#3
Sinister Between Trucks... Join Date: Mar 2002 Location: Los Angeles, CA. Posts: 3,830	long tail shaft if you have 2 wheel drive... the drive shaft is different for a 400... check out... [url]http://my.en.com/~thall/olds/oftrn.htm[url/] __________________ Beat it to fit, Paint it to match...

07-08-2002, 11:11 AM	#5
BLACK AND BLUE 67-72 Firefighter Join Date: Feb 2001 Location: Yellville, Ar, USA Posts: 1,943	Thanks Guys!!! __________________ '72 Chevy SWB 350 Auto '67 GMC LWB 350 4 speed '70 Chevy 4x4 Stepside 350 Auto Yellville, Ar. USA

07-08-2002, 12:07 AM	#4
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,690	The 400 has a longer overall length too. You'll have to move your cross member back, shorten your shaft, and get a new yolk. Over an inch longer than the TH350 short shaft that was origianl in our trucks. I'd just find a TH350 IMO.



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