6cyl tranny crossmember location vs 8cyl - The 1947 - Present Chevrolet & GMC Truck Message Board Network

grancuda · 06-08-2009, 11:19 PM

I have a factory '72 GMC LWB 6cyl man 3 speed on the column that I am swapping the motor. I bought a factory '71 GMC LWB 350 w/3 speed manual that has a hurst Indy shifter. The '71 has a 40k mile GM 260hp crate motor, new exaust, HD Radiator(on SPID) but the truck is in sad shape vs my low mileage '72.

I am planning on swapping the motor, radiator, exhaust system, rear leaf springs, and then moving the '71 with the 6 cyl.

Can I mount the 250 6cyl in the front position and run an electric fan? Can the z bar work on the 6 cyl in this position?
Should I remove the rivets holding the transmission cross member? What would that do to the floor shifter, move it back?
Could I swap out the front drive shafts to make up the difference in themounting position?

I would really prefer to leave the cross member where it is and just put the 6 cyl in the forward position on the one that is going.

BarryB · 06-09-2009, 12:10 AM

From what I can tell. you basically want to swap motors and such from one truck to the other?? If so, it should work with out any problems. I am pretty sure the transmounts/crossmembers are in the same spot regardless of which motor was in the trucks. The zbar IIRC is mounted to the bellhousing anyways, so yes it should work with your swap. Why are you wanting to run an electric fan? just swap everything from one to the other and be done with it.
my .02

grancuda · 06-09-2009, 08:06 AM

Yes, I am pretty much just wanting to swap out the motors.
The tranny crossmember is further forward on the 8 cyl.
The engine mounts are further forward on the 8 cyl.
I would have to run an electric fan possibly because my current fan would be in the radiator if I were to put the 6cyl in the 8cyl truck in its current configuration.

06-08-2009, 11:19 PM	#1
grancuda Registered User Join Date: Nov 2007 Location: Central OK Posts: 396	6cyl tranny crossmember location vs 8cyl I have a factory '72 GMC LWB 6cyl man 3 speed on the column that I am swapping the motor. I bought a factory '71 GMC LWB 350 w/3 speed manual that has a hurst Indy shifter. The '71 has a 40k mile GM 260hp crate motor, new exaust, HD Radiator(on SPID) but the truck is in sad shape vs my low mileage '72. I am planning on swapping the motor, radiator, exhaust system, rear leaf springs, and then moving the '71 with the 6 cyl. Can I mount the 250 6cyl in the front position and run an electric fan? Can the z bar work on the 6 cyl in this position? Should I remove the rivets holding the transmission cross member? What would that do to the floor shifter, move it back? Could I swap out the front drive shafts to make up the difference in themounting position? I would really prefer to leave the cross member where it is and just put the 6 cyl in the forward position on the one that is going.

06-09-2009, 12:10 AM	#2
BarryB Senior Member Join Date: Jul 2006 Location: Blountville, Tn. Posts: 3,904	Re: 6cyl tranny crossmember location vs 8cyl From what I can tell. you basically want to swap motors and such from one truck to the other?? If so, it should work with out any problems. I am pretty sure the transmounts/crossmembers are in the same spot regardless of which motor was in the trucks. The zbar IIRC is mounted to the bellhousing anyways, so yes it should work with your swap. Why are you wanting to run an electric fan? just swap everything from one to the other and be done with it. my .02 __________________ We could learn a lot from crayons... Some are sharp; some are pretty;and some are dull. Some have weird names; and all are different colours;but they all have to live in the same box. You may be only one person in the world, But you may also be the world to one person. * Some mistakes are too much fun to only make once. Two rules in life. 1. Never sweat the small stuff! 2. Everything is small stuff! Last edited by BarryB; 06-09-2009 at 12:10 AM.

06-09-2009, 08:06 AM	#3
grancuda Registered User Join Date: Nov 2007 Location: Central OK Posts: 396	Re: 6cyl tranny crossmember location vs 8cyl Yes, I am pretty much just wanting to swap out the motors. The tranny crossmember is further forward on the 8 cyl. The engine mounts are further forward on the 8 cyl. I would have to run an electric fan possibly because my current fan would be in the radiator if I were to put the 6cyl in the 8cyl truck in its current configuration.



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