Tranny X-member q'tion: 68 standard vs. 71 auto - The 1947 - Present Chevrolet & GMC Truck Message Board Network

BigSky71 · 02-23-2005, 07:01 PM

I noticed that when I removed the motor and tranny from my '71 that the crossmember on that truck is flat on top where the tail of the transmission bolts on [its an auto]. But on my 68 SWB frame [truck was 4-speed] that the crossmember is rounded where my tranny would mount. So I am hoping that I just need to buy an automatic transmission mount for a 68 frame to mount my TH350, or do I need to swap the crossmembers? Hope I don't have to switch them, the 68 framed is already primed and painted. Thanks for any help.

Putter · 02-23-2005, 09:03 PM

If it is rivited in place and of the top two rivits you can only see one (looking from the engine bay rearwards) and the other one is hidden by the cab, then you the standard-shift one and will need to replace it. I just finished that on mine Monday. PITA getting to those hidden rivits, but it can be done. The automatic crossmember will mount farther towards the rear.

BigSky71 · 02-23-2005, 09:56 PM

So it is a different setup, I will change it over. I have good access as both frames will be stripped of the cabs when that time comes. So to re-attach the crossmember I can just use appropriately sized Grade 8 bolts and nuts I presume? Thanks again.

purple gas · 02-24-2005, 03:40 AM

Much easier job with the cabs off. I just used grade 8 bolts myself. If I remember correctly there's a couple extra holdes in the frame, so make sure your tranny fits proper beffore you mount your cab, or at least put your bolts in so they can be removed if things don't line up.

Putter · 02-24-2005, 09:12 AM

I agree with P-Gas. I am sliding the motor/tranny into mine before I tighten down the cross-member. That way I can move it if I have mis-judged my location by a hole ot two.

BigSky71 · 02-25-2005, 12:37 PM

Thanks for help guys. I ground the rivets down and pulled the standard tranny mount out. I wish I had known earlier, I probably spend a few extra hours cleaning and painting that portion of the frame

, well now I know!

*dtlilly* · 02-25-2005, 12:49 PM

You are doing it, and doing it correctly! Gives the rest of us confidence that it's not as bad as it looks. Make sure to take plenty of pics, maybe you can post a "how to" thread in the FAQ section!

BigSky71 · 02-25-2005, 04:28 PM

Well here is the current state of my project. Yellow '71 Cheyenne going onto short frame that is now clean and black... but needing the auto tranny cross member from the lwb frame.

Notice there is no snow, its February in Montana but no moisture for us, sucks really. But it does make it easier to rebuild my truck this time of year.

02-23-2005, 07:01 PM	#1
BigSky71 LAIDOUT Join Date: Jan 2005 Location: NW Montana Posts: 928	Tranny X-member q'tion: 68 standard vs. 71 auto I noticed that when I removed the motor and tranny from my '71 that the crossmember on that truck is flat on top where the tail of the transmission bolts on [its an auto]. But on my 68 SWB frame [truck was 4-speed] that the crossmember is rounded where my tranny would mount. So I am hoping that I just need to buy an automatic transmission mount for a 68 frame to mount my TH350, or do I need to swap the crossmembers? Hope I don't have to switch them, the 68 framed is already primed and painted. Thanks for any help. __________________ 67 2wd Shorty Build Pictures

02-23-2005, 09:03 PM	#2
Putter More Cowbell.... Join Date: Mar 2004 Location: Puckett, MS Posts: 3,569	If it is rivited in place and of the top two rivits you can only see one (looking from the engine bay rearwards) and the other one is hidden by the cab, then you the standard-shift one and will need to replace it. I just finished that on mine Monday. PITA getting to those hidden rivits, but it can be done. The automatic crossmember will mount farther towards the rear. __________________ *There once was a member from Puckett.....Who ( fill in the blank blank blank* ) bucket**

02-23-2005, 09:56 PM	#3
BigSky71 LAIDOUT Join Date: Jan 2005 Location: NW Montana Posts: 928	So it is a different setup, I will change it over. I have good access as both frames will be stripped of the cabs when that time comes. So to re-attach the crossmember I can just use appropriately sized Grade 8 bolts and nuts I presume? Thanks again. __________________ 67 2wd Shorty Build Pictures

02-24-2005, 03:40 AM	#4
purple gas Registered User Join Date: Oct 2004 Location: saskatoon, planet earth Posts: 685	Much easier job with the cabs off. I just used grade 8 bolts myself. If I remember correctly there's a couple extra holdes in the frame, so make sure your tranny fits proper beffore you mount your cab, or at least put your bolts in so they can be removed if things don't line up. __________________ I got a bench seat baby, you don't have to sit over there.

02-24-2005, 09:12 AM	#5
Putter More Cowbell.... Join Date: Mar 2004 Location: Puckett, MS Posts: 3,569	I agree with P-Gas. I am sliding the motor/tranny into mine before I tighten down the cross-member. That way I can move it if I have mis-judged my location by a hole ot two. __________________ *There once was a member from Puckett.....Who ( fill in the blank blank blank* ) bucket**

02-25-2005, 12:37 PM	#6
BigSky71 LAIDOUT Join Date: Jan 2005 Location: NW Montana Posts: 928	Thanks for help guys. I ground the rivets down and pulled the standard tranny mount out. I wish I had known earlier, I probably spend a few extra hours cleaning and painting that portion of the frame , well now I know! __________________ 67 2wd Shorty Build Pictures

02-25-2005, 12:49 PM	#7
dtlilly Account Suspended Join Date: Jan 2003 Location: Shadow of Lambeau Field Posts: 5,597	You are doing it, and doing it correctly! Gives the rest of us confidence that it's not as bad as it looks. Make sure to take plenty of pics, maybe you can post a "how to" thread in the FAQ section!

02-25-2005, 04:28 PM	#8
BigSky71 LAIDOUT Join Date: Jan 2005 Location: NW Montana Posts: 928	Well here is the current state of my project. Yellow '71 Cheyenne going onto short frame that is now clean and black... but needing the auto tranny cross member from the lwb frame. Notice there is no snow, its February in Montana but no moisture for us, sucks really. But it does make it easier to rebuild my truck this time of year. __________________ 67 2wd Shorty Build Pictures



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