Finding Centerline 72 GTO GM A body to square up rear end

CraigG · 09-10-2025, 01:56 PM

Hey Everybody,

I'm trying to find centerline on 72 GTO With stock frame for measurements

Would it be halfway between?

Outer rocker panels
Center of transmission or transmission crossmember
Center of stock frame

Thanks, Craig

cordoba13 · 09-10-2025, 05:41 PM

most cars I have seen have offset for steering box/engine clearance, not sure about GTO?

CMcAllister · 09-10-2025, 10:36 PM

I would drop a string line from 4 or 5 different places on each side of the frame, from front to rear. Obviously use the same point on each side - suspension mounting points, factory locator holes, etc. Mark on the floor and find the center. If they all don't fall on the same line, double check your locations. And hope the car hasn't been hit.

Driveline is offset to the right. Don't recall the measurement but should be parallel with the chassis centerline.

mike britt · 09-10-2025, 11:11 PM

If you're trying to find centerline of the body, use a plumb bob from the trunk lock to the floor and the center of the grill to the floor.

rallye bob · Yesterday, 10:48 AM

Quote:

Originally Posted by CraigG

Hey Everybody,

I'm trying to find centerline on 72 GTO With stock frame for measurements

Would it be halfway between?

Outer rocker panels
Center of transmission or transmission crossmember
Center of stock frame

Thanks, Craig

https://www.chevelles.com/media/68-7...ensions.15066/

Troy Henderson · Yesterday, 11:19 AM

Quote:

Originally Posted by rallye bob

https://www.chevelles.com/media/68-7...ensions.15066/

A nice way to do it is to use the holes in the bottom of the frame shown in the link above. Then, you can drop multiple points down with a plumb bob to the ground on both sides. Measure across to get centers than take a string or laser and draw the centerline thru them.

Hacksaw · Yesterday, 03:37 PM

Pretty sure the engine centerline is offset to the pass side by 5/8".

Mark Yacavone · Yesterday, 06:13 PM

I seem to remember that the factory shop manuals had those frame directions in them. If I am recalling correctly then the GTO material should be easy enough to find.

FED 387 · Today, 12:03 AM

supposedly in all GM A-Body cars the engine is installed on the centerline NO offset from the factory --HOWEVER the pinion center was offset 1/2 inch to the passenger side of the vehicle--- not sure but what has been said-- might want to google it see what you can come up with

CraigG · Today, 11:02 AM

Thank you guys - very Helpful!

09-10-2025, 01:56 PM	#1
CraigG Junior Member Join Date: May 2007 Location: Iowa Posts: 42 Likes: 0 Liked 8 Times in 7 Posts	Finding Centerline 72 GTO GM A body to square up rear end Hey Everybody, I'm trying to find centerline on 72 GTO With stock frame for measurements Would it be halfway between? Outer rocker panels Center of transmission or transmission crossmember Center of stock frame Thanks, Craig

09-10-2025, 05:41 PM	#2
cordoba13 Junior Member Join Date: Aug 2023 Location: westerly RI Posts: 18 Likes: 1 Liked 13 Times in 8 Posts	Re: Finding Centerline 72 GTO GM A body to square up rear en most cars I have seen have offset for steering box/engine clearance, not sure about GTO?

09-10-2025, 10:36 PM	#3
CMcAllister Senior Member Join Date: Sep 2006 Location: Fulton County, PA Posts: 622 Likes: 17 Liked 929 Times in 263 Posts	Re: Finding Centerline 72 GTO GM A body to square up rear en I would drop a string line from 4 or 5 different places on each side of the frame, from front to rear. Obviously use the same point on each side - suspension mounting points, factory locator holes, etc. Mark on the floor and find the center. If they all don't fall on the same line, double check your locations. And hope the car hasn't been hit. Driveline is offset to the right. Don't recall the measurement but should be parallel with the chassis centerline.

09-10-2025, 11:11 PM	#4
mike britt Member Join Date: Mar 2013 Location: Italy, Texas Posts: 178 Likes: 379 Liked 66 Times in 31 Posts	Re: Finding Centerline 72 GTO GM A body to square up rear en If you're trying to find centerline of the body, use a plumb bob from the trunk lock to the floor and the center of the grill to the floor.

Yesterday, 03:37 PM	#7
Hacksaw Senior Member Join Date: Sep 2016 Posts: 887 Likes: 210 Liked 314 Times in 177 Posts	Re: Finding Centerline 72 GTO GM A body to square up rear en Pretty sure the engine centerline is offset to the pass side by 5/8".

Yesterday, 06:13 PM	#8
Mark Yacavone Veteran Member Join Date: Mar 2002 Location: Miles From Nowhere Posts: 7,838 Likes: 2,931 Liked 5,148 Times in 1,965 Posts	Re: Finding Centerline 72 GTO GM A body to square up rear en I seem to remember that the factory shop manuals had those frame directions in them. If I am recalling correctly then the GTO material should be easy enough to find. __________________ "We are lucky we don't get as much Government as we pay for." Will Rogers

Today, 12:03 AM	#9
FED 387 VIP Member Join Date: Jun 2006 Posts: 3,428 Likes: 560 Liked 335 Times in 182 Posts	Re: Finding Centerline 72 GTO GM A body to square up rear en supposedly in all GM A-Body cars the engine is installed on the centerline NO offset from the factory --HOWEVER the pinion center was offset 1/2 inch to the passenger side of the vehicle--- not sure but what has been said-- might want to google it see what you can come up with

Today, 11:02 AM	#10
CraigG Junior Member Join Date: May 2007 Location: Iowa Posts: 42 Likes: 0 Liked 8 Times in 7 Posts	Re: Finding Centerline 72 GTO GM A body to square up rear en Thank you guys - very Helpful!