recent purchase/Drivetrain swap - The 1947 - Present Chevrolet & GMC Truck Message Board Network

onefine69 · 05-14-2002, 02:16 AM

I have just purchased a 1969 GMC 910 Custom, it has an inline 6 and 2 speed powerglde tranny. I already have a thm400 and was wondering what kind of problems guys have ran into swaping out the old power train for the new one. I plan on putting a 383 stroker into this truck with the aforementioned trans. I also want to swap the front end over for disc brakes and change the rear end to handle the HP as well as converting over to 5 lug wheels. Any suggestions at all would be helpful as this is my first project. Thanks, Great forum too!!!!

Mike C · 05-14-2002, 06:40 AM

The turbo 400 is longer than the powerglide and will require a shorter driveshaft as well as a different output shaft yoke. I would mount the V8 on the 6 cylinder frame mounts as it gets the weight further back for better handling and increased rear wheel traction. You might have troubles running a large cap HEI however. If you get a TH350 and use the 6 cylinder mounts you can keep your existing driveshaft.

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70 GMC 3/4 ton Sierra Grande 402/TH400
72 Jimmy 4WD 4spd 4" & 35's
64 Corvette Coupe
68 Camaro 'vert TPI & TH700
69 Z/28 355 12.6's @110
72 Datsun 240Z-ol' reliable

69 longhorn · 05-14-2002, 07:12 AM

I have mine set up on 6/250 stands,& the HEI is tight but does fit. What I like to do is drill the eng mount holes in the stands to 5/8",& slot the trans crossmember holes. This gives a little adjustment......not a lot,but just enough for the HEI. If you already have a good 400T,I would use it,the placement of the crossmember will be different,& as posted it will be a little longer(about 11/16"for the short tail),than a 350T. It is pretty cheap to shorten & balance a shaft,or you can go to a 1 pc shaft(4" diameter in the 6' lenght range). Up front,I used the 73 up long waterpump & accessories to put the fan in proper location with the radiator. In the ex department,with an auto trans.......pretty much anything goes. I have a set of 2452 Hooker comps,& good ground clearance.......or you can run the straight dump 2 1/2" Vette ram horns (in 6 cyl position ). Good luck.....69longhorn.

onefine69 · 05-14-2002, 11:19 AM

Thanks for the info guys. Any other sugestions anyone may have would be greatly appreciated.

05-14-2002, 02:16 AM	#1
onefine69 Registered User Join Date: May 2002 Location: Drumheller, Alberta, Canada Posts: 2	recent purchase/Drivetrain swap I have just purchased a 1969 GMC 910 Custom, it has an inline 6 and 2 speed powerglde tranny. I already have a thm400 and was wondering what kind of problems guys have ran into swaping out the old power train for the new one. I plan on putting a 383 stroker into this truck with the aforementioned trans. I also want to swap the front end over for disc brakes and change the rear end to handle the HP as well as converting over to 5 lug wheels. Any suggestions at all would be helpful as this is my first project. Thanks, Great forum too!!!!

05-14-2002, 06:40 AM	#2
Mike C Registered User Join Date: Dec 1999 Location: Austin, TX, USA Posts: 7,715	The turbo 400 is longer than the powerglide and will require a shorter driveshaft as well as a different output shaft yoke. I would mount the V8 on the 6 cylinder frame mounts as it gets the weight further back for better handling and increased rear wheel traction. You might have troubles running a large cap HEI however. If you get a TH350 and use the 6 cylinder mounts you can keep your existing driveshaft. ------------------ 70 GMC 3/4 ton Sierra Grande 402/TH400 72 Jimmy 4WD 4spd 4" & 35's 64 Corvette Coupe 68 Camaro 'vert TPI & TH700 69 Z/28 355 12.6's @110 72 Datsun 240Z-ol' reliable __________________ 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

05-14-2002, 07:12 AM	#3
69 longhorn Registered User Join Date: Aug 2001 Location: rock island,il,usa Posts: 5,382	I have mine set up on 6/250 stands,& the HEI is tight but does fit. What I like to do is drill the eng mount holes in the stands to 5/8",& slot the trans crossmember holes. This gives a little adjustment......not a lot,but just enough for the HEI. If you already have a good 400T,I would use it,the placement of the crossmember will be different,& as posted it will be a little longer(about 11/16"for the short tail),than a 350T. It is pretty cheap to shorten & balance a shaft,or you can go to a 1 pc shaft(4" diameter in the 6' lenght range). Up front,I used the 73 up long waterpump & accessories to put the fan in proper location with the radiator. In the ex department,with an auto trans.......pretty much anything goes. I have a set of 2452 Hooker comps,& good ground clearance.......or you can run the straight dump 2 1/2" Vette ram horns (in 6 cyl position ). Good luck.....69longhorn. __________________ http://community.webshots.com/user/hotrodhorn

05-14-2002, 11:19 AM	#4
onefine69 Registered User Join Date: May 2002 Location: Drumheller, Alberta, Canada Posts: 2	Thanks for the info guys. Any other sugestions anyone may have would be greatly appreciated.



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