Mystery Firewall Hole - The 1947 - Present Chevrolet & GMC Truck Message Board Network

LongBox · 11-06-2016, 08:22 PM

Here are two photos of the mysterious oval-shaped hole in my firewall. Just guessing, I'd say the hole was to accommodate an overdrive control rod, but I don't really know. Can anybody confirm, or tell what its purpose was.

You can see that mine was covered with tape, appears to have been that way since new. I found a proper blanking plate at a boneyard, and installed it today.

lowrollin70gmc · 11-06-2016, 08:34 PM

That hole is for the clutch linkage on manual trans trucks.

LongBox · 11-06-2016, 09:00 PM

Thanks. And I have absolutely no idea why the photos got rotated.

ratty69 · 11-06-2016, 09:16 PM

Quote:

Originally Posted by LongBox

I found a proper blanking plate...

I didn't know such an animal existed. What did those come on? Was going to make one, but that looks way better.

**truckster** · 11-06-2016, 10:06 PM

Quote:

Originally Posted by ratty69

I didn't know such an animal existed. What did those come on? Was going to make one, but that looks way better.

Mine came from the factory that way (TH350 transmission).

ratty69 · 11-06-2016, 10:25 PM

So any auto truck SHOULD have had one? Good to know. Thanks.

LongBox · 11-06-2016, 10:41 PM

Yes, mine came off a bone yard donor 71 or 72, with an auto trans. Had to pay $5, sheesh!

**FirstOwner69** · 11-06-2016, 10:51 PM

The metal plates were used for at least 71 and 72. 69s and earlier had silver plastic plugs. Not sure which 70s used, but I think the plugs. If yours is missing and there are no screw holes, it had a plug from the factory. The plugs were put in from the driver side and frequently popped out when the doors of the cabs were closed. New plugs are available here: http://67-72chevytrucks.com/vboard/s...=clutch+delete

The plates are frequently listed on the for sale forum. Just search that forum for "clutch delete

Here's the plug in my 69.

Kw69 · 11-06-2016, 10:55 PM

Hey guys I dint need the plug but I need that grommet for my 69,.. Anybody know where I can find one? My is gone and I have an open hole with the rod coming through... Funny I was just about to post this and the OP beat me to it. Sorry to hijack the thread OP. Thanks

ratty69 · 11-06-2016, 11:27 PM

Thanks guys, especially FirstOwner69 for the detailed reply and link. The plug does look much cleaner, but staying put is important too. Mine was 4spd so no plug either way. When I can ditch the th350 and go back to manual I think I'll probably use the bolt on kind.

**Already Gone** · 11-07-2016, 12:34 PM

Quote:

Originally Posted by LongBox

Here are two photos of the mysterious oval-shaped hole in my firewall. Just guessing, I'd say the hole was to accommodate an overdrive control rod, but I don't really know. Can anybody confirm, or tell what its purpose was.

You can see that mine was covered with tape, appears to have been that way since new. I found a proper blanking plate at a boneyard, and installed it today.

I can help with the sideways pics. I had the same problem with my IPhone pics and was told by a board member if you hold the phone sideways with the bottom button on your right the pics will post properly when you post them on this site and any other for that matter. I would say its the same for a Galaxy phone but not 100% sure, maybe someone on here can chime in with that info.

57larry · 11-07-2016, 10:06 PM

I just welded a plug in my hole, body worked it, paint, can't tell it was there

Econman · 11-07-2016, 11:15 PM

Quote:

Originally Posted by 57larry

I just welded a plug in my hole, body worked it, paint, can't tell it was there

I did the same thing.

11-06-2016, 08:22 PM	#1
LongBox Registered User Join Date: Sep 2016 Location: Vancouver BC Posts: 784	Mystery Firewall Hole Here are two photos of the mysterious oval-shaped hole in my firewall. Just guessing, I'd say the hole was to accommodate an overdrive control rod, but I don't really know. Can anybody confirm, or tell what its purpose was. You can see that mine was covered with tape, appears to have been that way since new. I found a proper blanking plate at a boneyard, and installed it today. Attached Images __________________ Rick -69 GMC 910 Long Box, 350 -98 Chev Silverado 1500, 350 Vortec 4L60e -08 Mustang GT Convertible

11-06-2016, 08:34 PM	#2
lowrollin70gmc Too many projects Join Date: Mar 2004 Location: Fargo, ND land of the flat hills Posts: 1,147	Re: Mystery Firewall Hole That hole is for the clutch linkage on manual trans trucks. __________________ Andrew 84 GMC C1500 SWB 6.2 Diesel/700R4/3.42 "Grandpa's odd duck" 70 GMC C1500 LWB My first truck: shaved, bagged, and more: the lowrollin70gmc 68 K20 Suburban 12V Cummins/NV5600/NP205/D60/11.5AAM 3.73s "Dakota Cadillac" 63 Chevy II Nova Coupe 250 I6/T56/4.56s "Economy car" 53 Willys Wagon 350/NV4500/BW4401/HP D44/9inch “Winter Wagon” 30 Model A 16 Focus ST

11-06-2016, 09:00 PM	#3
LongBox Registered User Join Date: Sep 2016 Location: Vancouver BC Posts: 784	Re: Mystery Firewall Hole Thanks. And I have absolutely no idea why the photos got rotated. __________________ Rick -69 GMC 910 Long Box, 350 -98 Chev Silverado 1500, 350 Vortec 4L60e -08 Mustang GT Convertible

11-06-2016, 10:25 PM	#6
ratty69 Registered User Join Date: Jun 2016 Location: Vancouver B.C. Posts: 206	Re: Mystery Firewall Hole So any auto truck SHOULD have had one? Good to know. Thanks.

11-06-2016, 10:41 PM	#7
LongBox Registered User Join Date: Sep 2016 Location: Vancouver BC Posts: 784	Re: Mystery Firewall Hole Yes, mine came off a bone yard donor 71 or 72, with an auto trans. Had to pay $5, sheesh! __________________ Rick -69 GMC 910 Long Box, 350 -98 Chev Silverado 1500, 350 Vortec 4L60e -08 Mustang GT Convertible

11-06-2016, 10:51 PM	#8
FirstOwner69 Senior Member Join Date: May 2010 Location: Wisconsin & Arizona Posts: 4,852	Re: Mystery Firewall Hole The metal plates were used for at least 71 and 72. 69s and earlier had silver plastic plugs. Not sure which 70s used, but I think the plugs. If yours is missing and there are no screw holes, it had a plug from the factory. The plugs were put in from the driver side and frequently popped out when the doors of the cabs were closed. New plugs are available here: http://67-72chevytrucks.com/vboard/s...=clutch+delete The plates are frequently listed on the for sale forum. Just search that forum for "clutch delete Here's the plug in my 69. Attached Images Last edited by FirstOwner69; 11-06-2016 at 10:59 PM.

11-06-2016, 10:55 PM	#9
Kw69 Registered User Join Date: Sep 2015 Location: Florida Posts: 111	Re: Mystery Firewall Hole Hey guys I dint need the plug but I need that grommet for my 69,.. Anybody know where I can find one? My is gone and I have an open hole with the rod coming through... Funny I was just about to post this and the OP beat me to it. Sorry to hijack the thread OP. Thanks __________________ 2009 GMC 2500HD 6.0, 6 speed auto, stealth grey, 4x4 Z71, Bilsteins, Black Bear Tuned. Pulls the 10k fifth wheel all so easy. 1969 CST 350 black long bed, 3 on the floor, PS, AC, drum brakes, old school and love it.

11-06-2016, 11:27 PM	#10
ratty69 Registered User Join Date: Jun 2016 Location: Vancouver B.C. Posts: 206	Re: Mystery Firewall Hole Thanks guys, especially FirstOwner69 for the detailed reply and link. The plug does look much cleaner, but staying put is important too. Mine was 4spd so no plug either way. When I can ditch the th350 and go back to manual I think I'll probably use the bolt on kind.

11-07-2016, 10:06 PM	#12
57larry Registered User Join Date: Nov 2007 Location: Indianapolis Posts: 1,161	Re: Mystery Firewall Hole I just welded a plug in my hole, body worked it, paint, can't tell it was there

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