Conversion Guru's help! - The 1947 - Present Chevrolet & GMC Truck Message Board Network

super72bb · 10-09-2002, 05:43 AM

A friend of mine is replacing his stock 2 speed powerglide with a TH400. In his 68 2WD 1/2 ton. He is also changing the stock 6 bolt rear end to a 5 bolt.

My questions are.... what modifications are needed as far as cross member, mounts, or linkage if any. The driveshaft needs to be shortened does anyone know how long the shaft should be off hand. Is there any size difference between the earlier 6 bolt rear end caps (U-joint caps) and the 5 bolt stlye? Or will the same size u-joints work.

If there is any other tips you may have with this conversion to help that would be awesome.

Thanks everyone

slam33 · 10-09-2002, 10:11 AM

Doing a turbo 350 would be a staight in swap, the 400 need a shorter drive shaft, and the linkage package is differant. You also need the 3 speed steering colume, starter might be differant as might be the flex plate. What does he have for a motor. A SBC works best with a Turbo 350 as the 400 will eat about 30 hp to drive it.

Longhorn Man · 10-09-2002, 11:00 PM

one thing slam left out on the 400 deal is the yolk. The TH400 has a unique yolk.

Mike C · 10-10-2002, 08:20 AM

U-joints should be same. As noted, TH350 will drop right in place of powerglide. Takes 48hp to turn a TH400 in top gear compated to 35 hp with a TH350 NOT a 30 hp difference, but 13.

10-09-2002, 05:43 AM	#1
super72bb Senior Member Join Date: Jan 2002 Location: calgary,Alberta,Canada Posts: 387	Conversion Guru's help! A friend of mine is replacing his stock 2 speed powerglide with a TH400. In his 68 2WD 1/2 ton. He is also changing the stock 6 bolt rear end to a 5 bolt. My questions are.... what modifications are needed as far as cross member, mounts, or linkage if any. The driveshaft needs to be shortened does anyone know how long the shaft should be off hand. Is there any size difference between the earlier 6 bolt rear end caps (U-joint caps) and the 5 bolt stlye? Or will the same size u-joints work. If there is any other tips you may have with this conversion to help that would be awesome. Thanks everyone __________________ 1972 CHEYENNE SUPER SWB BLACK. 402 BB, TH400, AIR, TILT, TACH, BUCKETS, CRUISE, AM/FM, 8 TRACK. My build thread: http://67-72chevytrucks.com/vboard/s...=1#post7120181

10-09-2002, 10:11 AM	#2
slam33 Registered User Join Date: Aug 2001 Location: Long Beach, Ca Posts: 1,432	Doing a turbo 350 would be a staight in swap, the 400 need a shorter drive shaft, and the linkage package is differant. You also need the 3 speed steering colume, starter might be differant as might be the flex plate. What does he have for a motor. A SBC works best with a Turbo 350 as the 400 will eat about 30 hp to drive it. __________________ 71 LWB 350/350still working on it but it's going tp be sweet. www.geocities.com/stevemau/slam33page.html " TARGET=_blank>http://www.geocities.com/stevemau/slam33page.html?1004806705410 </A>

10-10-2002, 08:20 AM	#4
Mike C Registered User Join Date: Dec 1999 Location: Austin, TX, USA Posts: 7,728	U-joints should be same. As noted, TH350 will drop right in place of powerglide. Takes 48hp to turn a TH400 in top gear compated to 35 hp with a TH350 NOT a 30 hp difference, but 13. __________________ 44 Willys MB 52 M38A1 64 Corvette Coupe 68 Camaro 'vert LT1 & TH700 69 Z/28 355 12.6's @110 69 Chevy Short Step 4 1/2"/7" drop 72 Jimmy 4WD 4spd 4" & 35's 02 GMC 2500HD 4x4 Duramax

10-09-2002, 11:00 PM	#3
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,690	one thing slam left out on the 400 deal is the yolk. The TH400 has a unique yolk.



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