73-80,4x4 tunnel, tips - The 1947 - Present Chevrolet & GMC Truck Message Board Network

madcow75 · 01-21-2012, 07:09 PM

I am looking for some opinions from the 67-72,,73-80,,and the 81-87(91) 4x4 cab owners. I have a 1976 C30 doing a 4x4 conversion so I am putting in the tranny high tunnnel in my 2wd cab. My question is should I weld in my bolt in tunnel like the 81-91 cab tunnels are. I am thinking of doing this for cab strength. Would it be recommended to make it solid. I am also running a manual tranny, for now it will be a sm465. How many times do you manual tranny guys really take the tunnel off, that I should leave it a bolt in? The whole in the floor seems to me like it would be a weak point in the cab. I have been told many guys have folded up cabs with the gapping hole in the floor. Just looking for some opinions of experienced owners.

Chevy1TonFun · 01-22-2012, 12:45 AM

I say leave it a bolt in. What is your plan with your truck.

madcow75 · 01-22-2012, 12:18 PM

My plan is 1976 CC dually , 6.5TD,sm465,np205 on Dana60,Dana70HD with Powr-lok's 410's on 325/85/16 which are 38's , military xlm michelin's. I might later switch tranny to a nv4500. It will mainly be a street truck with the occational need to go off road hunting.

Chevy1TonFun · 01-22-2012, 01:10 PM

I see no reason to weld the tunnel in if that all you are going to do. I have taken my tunnel cover off a few times. I can help at times.

madcow75 · 01-22-2012, 08:27 PM

Do you have any problems with water getting in under the carpet or rubber mat being a bolt in, or do you silicone the crap out of it. Seems like it would be a good spot for water to layon the lip and cause cab rot. Origanally from the factory I no there was a foam seal.

odog · 01-23-2012, 12:26 AM

I just got done putting the tranny and tcase in my 69 and I can say without a doubt that the bolt on tunnel was a huge help. You can acess the bellhousing bolts without having to reach around from the bottom, you can take the top off the trans if needed, there are a lot of uses for the bolt on tunnel. As for water, mine had a bead of some sort of sealer when I took the tunnel off and it never leaked water before. I am assuming it wasnt factory as it looked like roofing caulk, but it worked. You are saying you may gotto an NV later on, for me that would be reason enough to leave the bolt on tunnel.

Just my .02, but you asked.

Erik

madcow75 · 01-23-2012, 06:06 AM

A bolt in it is. Cut the hole and welded some nuts to the floor yesterday. I forsure will need some kind of a sealant to stop the water from getting in and from getting trapped in the lip.

01-21-2012, 07:09 PM	#1
madcow75 Registered User Join Date: Jun 2009 Location: Fort Erie , Ontario Posts: 525	73-80,4x4 tunnel, tips I am looking for some opinions from the 67-72,,73-80,,and the 81-87(91) 4x4 cab owners. I have a 1976 C30 doing a 4x4 conversion so I am putting in the tranny high tunnnel in my 2wd cab. My question is should I weld in my bolt in tunnel like the 81-91 cab tunnels are. I am thinking of doing this for cab strength. Would it be recommended to make it solid. I am also running a manual tranny, for now it will be a sm465. How many times do you manual tranny guys really take the tunnel off, that I should leave it a bolt in? The whole in the floor seems to me like it would be a weak point in the cab. I have been told many guys have folded up cabs with the gapping hole in the floor. Just looking for some opinions of experienced owners.

01-22-2012, 12:45 AM	#2
Chevy1TonFun Grease Monkey Join Date: Oct 2007 Location: Fresno CA Posts: 750	Re: 73-80,4x4 tunnel, tips I say leave it a bolt in. What is your plan with your truck. __________________ Tow Rig: 2012 Chevy 2500HD CCSB LTZ Z71 4x4 Duramax Ultimate Offroad Build: 1978 Chevy Silverado K30 Crewcab Build Link http://67-72chevytrucks.com/vboard/s...d.php?t=654053 Mud Truck: 1972 Chevy Cheyenne K30 4x4, 468/400/205, D60/D70HD, 18" Custom Lift, 17x39" IROKs FOR SALE http://67-72chevytrucks.com/vboard/c...ton-4x4&cat=12

01-22-2012, 12:18 PM	#3
madcow75 Registered User Join Date: Jun 2009 Location: Fort Erie , Ontario Posts: 525	Re: 73-80,4x4 tunnel, tips My plan is 1976 CC dually , 6.5TD,sm465,np205 on Dana60,Dana70HD with Powr-lok's 410's on 325/85/16 which are 38's , military xlm michelin's. I might later switch tranny to a nv4500. It will mainly be a street truck with the occational need to go off road hunting.

01-22-2012, 01:10 PM	#4
Chevy1TonFun Grease Monkey Join Date: Oct 2007 Location: Fresno CA Posts: 750	Re: 73-80,4x4 tunnel, tips I see no reason to weld the tunnel in if that all you are going to do. I have taken my tunnel cover off a few times. I can help at times. __________________ Tow Rig: 2012 Chevy 2500HD CCSB LTZ Z71 4x4 Duramax Ultimate Offroad Build: 1978 Chevy Silverado K30 Crewcab Build Link http://67-72chevytrucks.com/vboard/s...d.php?t=654053 Mud Truck: 1972 Chevy Cheyenne K30 4x4, 468/400/205, D60/D70HD, 18" Custom Lift, 17x39" IROKs FOR SALE http://67-72chevytrucks.com/vboard/c...ton-4x4&cat=12

01-22-2012, 08:27 PM	#5
madcow75 Registered User Join Date: Jun 2009 Location: Fort Erie , Ontario Posts: 525	Re: 73-80,4x4 tunnel, tips Do you have any problems with water getting in under the carpet or rubber mat being a bolt in, or do you silicone the crap out of it. Seems like it would be a good spot for water to layon the lip and cause cab rot. Origanally from the factory I no there was a foam seal.

01-23-2012, 12:26 AM	#6
odog Registered User Join Date: Oct 2007 Location: Wendell, Idaho Posts: 608	Re: 73-80,4x4 tunnel, tips I just got done putting the tranny and tcase in my 69 and I can say without a doubt that the bolt on tunnel was a huge help. You can acess the bellhousing bolts without having to reach around from the bottom, you can take the top off the trans if needed, there are a lot of uses for the bolt on tunnel. As for water, mine had a bead of some sort of sealer when I took the tunnel off and it never leaked water before. I am assuming it wasnt factory as it looked like roofing caulk, but it worked. You are saying you may gotto an NV later on, for me that would be reason enough to leave the bolt on tunnel. Just my .02, but you asked. Erik __________________ 1969 4x4 Nothing beats a good rock drill and some dynamite

01-23-2012, 06:06 AM	#7
madcow75 Registered User Join Date: Jun 2009 Location: Fort Erie , Ontario Posts: 525	Re: 73-80,4x4 tunnel, tips A bolt in it is. Cut the hole and welded some nuts to the floor yesterday. I forsure will need some kind of a sealant to stop the water from getting in and from getting trapped in the lip.



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