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#1 |
Registered User
Join Date: Jun 2011
Location: cape cod ma
Posts: 160
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high hump low hump differences
ok so prob a goofy a#* question but is there a difference between a low hump tranny tunnel firewall and a high hump tunnel firewall
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1980 crewcab dually soon to have a gen VI 454 rectangular port heads holley strip dominator crusader marine stand alone tbi setup with a TCI tcu controlled 4L80 (daily driver) 92 harley electra glide ultra classic |
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#2 |
Senior Member
Join Date: May 2009
Location: Fort Worth, TX
Posts: 6,370
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Re: high hump low hump differences
The high hump was used to clear 4 speed manual transmissions, Yes they are different/larger than a low hump.
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#3 |
Registered User
Join Date: Jun 2011
Location: cape cod ma
Posts: 160
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Re: high hump low hump differences
I understand the humps heights are different I think I worded it wrong I'm wondering if there is a difference in the firewall
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1980 crewcab dually soon to have a gen VI 454 rectangular port heads holley strip dominator crusader marine stand alone tbi setup with a TCI tcu controlled 4L80 (daily driver) 92 harley electra glide ultra classic |
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#4 |
My Carbon Footprint
Join Date: Oct 2008
Location: Orygun
Posts: 5,527
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Re: high hump low hump differences
There may be a point where there is less clearance on the low hump as it starts to come up to the fire wall. The bolts are all the same though. You can take out a low hump and install a high one. I prefer the high hump because it kind of divides the driver's and pass area so it's not just one big flat looking floor board.
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#5 |
Registered User
Join Date: Jun 2011
Location: cape cod ma
Posts: 160
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Re: high hump low hump differences
ok the reason i was wondering is i plan on installing a bbc in my 67 and it has a high hump for the sm465 and i've read a few posts about firewall clearance and high hump low hump preference so i was wondering if high humps had more firewall clearance than low hump apps.
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1980 crewcab dually soon to have a gen VI 454 rectangular port heads holley strip dominator crusader marine stand alone tbi setup with a TCI tcu controlled 4L80 (daily driver) 92 harley electra glide ultra classic |
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#6 |
My Carbon Footprint
Join Date: Oct 2008
Location: Orygun
Posts: 5,527
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Re: high hump low hump differences
The truck above was a 250 6 cyl and sm 465. Is now a 460 BBC and M-22. Everything fit perfect....with a few mods but firewall wasn't even close to an issue.
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#7 |
Registered User
Join Date: Jun 2011
Location: cape cod ma
Posts: 160
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Re: high hump low hump differences
did you use the stock style motor stands or after market ?
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1980 crewcab dually soon to have a gen VI 454 rectangular port heads holley strip dominator crusader marine stand alone tbi setup with a TCI tcu controlled 4L80 (daily driver) 92 harley electra glide ultra classic |
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#8 | |
Senior Member
Join Date: May 2009
Location: Fort Worth, TX
Posts: 6,370
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Re: high hump low hump differences
Quote:
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#9 |
its all about the +6 inches
Join Date: Jan 2001
Location: Hilliard Ohio
Posts: 2,693
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Re: high hump low hump differences
the firewall is the same
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#10 |
My Carbon Footprint
Join Date: Oct 2008
Location: Orygun
Posts: 5,527
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Re: high hump low hump differences
No....I had the right BBC stands from a 68 custom camper with a 396.
Mine was an L6. Not sure what you mean. |
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#11 |
its all about the +6 inches
Join Date: Jan 2001
Location: Hilliard Ohio
Posts: 2,693
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Re: high hump low hump differences
A two wheel drive inline six with an automatic or 3 speed should have had a low hump that is part of the floor pan and not bolted in place.
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#12 |
My Carbon Footprint
Join Date: Oct 2008
Location: Orygun
Posts: 5,527
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Re: high hump low hump differences
Ah....that's good to know. So what the heck do you do when you want to convert?
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#13 |
Senior Member
![]() Join Date: Jan 2007
Location: Turlock, CA
Posts: 8,656
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Re: high hump low hump differences
bump... same question, what's involved with converting a low to a high? Just drilling the holes???
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Please help my sister in law with her battle with cancer https://gofund.me/902f6fce Project "C10 Fever" (68 factory black 396 swb) Project "Little Sister" (70 c10 blue original paint refresh) Project "Blue Bomb" (70 c30 blue original paint refresh) SOLD Project "Vitamin C" (71 c10 orange original paint refresh) SOLD |
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#14 |
Registered User
Join Date: Dec 2007
Location: Nanaimo B.C.
Posts: 604
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Re: high hump low hump differences
I got the big block stands and put a bbc in a low hump with a t400 with no problems
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I was hooked on these trucks since 1982 when I drove my budys fathers 1968 Custum GMC 396 automatic dana 60 rear with a power lock diff what a ride more fun then we will we can ever tell!! |
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#15 |
Registered User
![]() Join Date: Apr 2007
Location: Foster Rhode Island
Posts: 1,176
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Re: high hump low hump differences
Theres a depresion in the floor where you need to cut it out. then drill holes and use the clips like on a front fender for the bolts. Wait till you have the high hump and then you can better see where you will want to cut and how much.
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#16 |
1969 Custom 30 wrecker
Join Date: Sep 2001
Location: Pottsville, Pa
Posts: 2,611
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Re: high hump low hump differences
Installing a high hump is just a matter of cutting the hump out and drilling some holes. You'll also want to lightly roll the edge a bit. I just used a dolly and hammer, real easy.
I installed a new repro low hump floor pan into my wrecker and did as I mentioned. Firewalls are all the same. One other thing depending on how correct you want it. I welded square nuts on the bottom of the holes as the factory did. Real easy to do, just a few tack welds on each. New square nuts are available just about anywhere.
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Bob 63 Impala 283/PG/3.36 (under restoration) 66 Impala 327/PG/3.36 66 Chevelle SS 409/M22/3.55 69 Chevelle 307/PG/3.08 (future restoration) 69 C10 short stepside 454/TH350/3.73 69 Custom 30 tow truck 350/4 spd/4.10 (resto done, CRUISIN TIME!) 71 Cheyenne 20 fleetside 350/4 spd/4.10 71 Chevelle 6/PG/3.08 72 Chevelle 454/M21/4.10 |
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#17 |
Registered User
Join Date: Jun 2012
Location: Washington, NC
Posts: 35
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Re: high hump low hump differences
Can the high hump only be purchased used? I can't seem to find one anywhere.
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#18 |
Moderator
![]() Join Date: May 2007
Location: Southern Cal
Posts: 20,005
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Re: high hump low hump differences
Yes. They come up for sale here on the parts board all the time. You can look there for one, or if you become a subscribing member you can post a want-to-buy ad and I am sure someone will have one for sale.
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1972 C/10 Cheyenne Super SWB. Restored, loaded, slammed. 1968 C/10 50th Anniversary LWB. Unrestored, stock, daily driver/work truck. RIP ElJay RIP 67ChevyRedneck RIP Grumpy Old Man |
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#19 |
Registered User
Join Date: Jun 2012
Location: Washington, NC
Posts: 35
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Re: high hump low hump differences
Cool. Thanks.
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#20 |
Registered User
Join Date: Dec 2013
Location: washington north carolina
Posts: 123
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Re: high hump low hump differences
I know this is an old thread but, I'm putting together a 68 with 454 and muncie 4 speed. Will I have to convert to a high hump or will the low one work with the manual shift??
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#21 |
Account Suspended
![]() Join Date: Jul 2016
Location: Tacoma, WA
Posts: 6,873
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Re: high hump low hump differences
Muncie sm 465, truck trans with granny low should have the high hump so the boot etc fits right, car 4 spd m20, m21, m22 etc can use the low hump.
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#22 |
Registered User
Join Date: Dec 2013
Location: washington north carolina
Posts: 123
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Re: high hump low hump differences
Thanks Randy. That's what I needed to know. You saved me some work. I have the m20
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