Low Hump to High Hump conversion - The 1947 - Present Chevrolet & GMC Truck Message Board Network

1968SWBBigBlock · 07-23-2010, 03:11 PM

Can anyone give me a step by step procedure for replacing the low hump with a high hump in my 68?

gregg72340 · 07-23-2010, 03:49 PM

Bump I need it too

redbaron69 · 07-23-2010, 04:00 PM

me three... is the high hump a must have if you put in a big block? or is it the trans you use?

Sammy · 07-23-2010, 04:42 PM

Been awhile (15 yrs) since I done mine but sure someone will add to it. Remove the seat, carpet/ or mat and any thing on the floor for access. Carefully mark the floor with chalk for cutout. Remove anything under the floor ie D/S and tranny. Cut out the area with a torch / plasma cutter staying within the area you marked. Install the high hump and put your new mat or carpet in and seat. If your putting a tranny shift thru the floor you can install the high hump cover after the tranny.

gregg72340 · 07-23-2010, 09:28 PM

From what I have heard on here you need the high hump for the big block

Sammy · 07-23-2010, 10:03 PM

To hold the hump down since my cab was still installed I used some 1/2" or 7/16" diameter self tapping bolts, w/ washer and a small bit to pre-drill my location.

68 TT · 07-24-2010, 01:14 AM

Quote:

Originally Posted by gregg72340

From what I have heard on here you need the high hump for the big block

Not true. I had a big block in my 67 with the low hump. I was running it with a T-350 trans. The high hump may be needed with the T-400 as it is a bit thicker in the area behind the bell housing than a T-350 but I don't know for sure the T-400 won't clear a low hump.

Most likely it is really only needed with a 4x4 to clear the transfer case.

60ratrod · 07-24-2010, 01:29 AM

pretty much the only reason to go high hump is if you are switching from a th350(2wd) or the 3 on the tree(2wd). i don't remember if the 4wd versions needed the high hump or not. but the size of the popular saginaw and muncie 4 speeds as well as the th400 required the extra clearance. that's why when i swap cabs on my 72 i'm gonna look for a 4-5 speed that doesn't require the high hump and will allow me to use the stock 2 piece shaft

redbaron69 · 07-24-2010, 05:07 PM

good info on the trans part guys. if that the case i just keep my low hump and run a th350. thanks

**leddzepp** · 07-24-2010, 06:14 PM

I have seen trucks with a BBC/TH400 with a low hump cab.

vectorit · 07-24-2010, 06:28 PM

I know that on my burb with its high hump, while running an sm465 trans I could not run a low hump if I wanted to.
The t-case is behind the hump, but the shifter bracket pokes through the high hump.
I knew a guy that had a 69 GMC PU that he converted to 4x4.
It was an automatic, and he still ran the low hump.

1-PU70 · 07-24-2010, 06:58 PM

Im running a 402 with a 700R4 in a low hump.

haysonj · 07-24-2010, 07:47 PM

It all depends on how you want to set your motor. I have a 383, T400,208 transfer case, and a Gear Vendors OD all in a low hump C10 converted to a 3/4 ton 4x4.

Zeke · 07-25-2010, 08:43 AM

Someone correct me if I am wrong but they way I see it with the standard 4sp they put the high hump in there so you could get to the top cap just in case you needed to inspect the gears or change shifter balls so you wouldn't have to drop the tranny. If I remember those things weigh a ton. As far as other trucks with different engine transmission combos it was probably a money thing, its cheaper to make a cover than a different floor, if a truck was going down the line and a change was made or they didn't have low hump floor it got a high hump. Thats why you see trucks with the same engine/trans combo some with low and some with high humps.

Just my thinking, might be wrong though.

codeJbird · 09-07-2010, 02:56 PM

i've already cut out part of my floor for my tranny and i can't seem to find a 4x4 high hump anywhere. more like i'm looking in the wrong spot. i was told that it is a bolt in replacement.

codeJbird · 09-23-2010, 05:25 PM

anyone know where to find the high hump or 4x4 transmission tunnel for a replacement?

thnx,
bird

68 TT · 09-23-2010, 06:32 PM

Quote:

Originally Posted by vectorit

I know that on my burb with its high hump, while running an sm465 trans I could not run a low hump if I wanted to.
The t-case is behind the hump, but the shifter bracket pokes through the high hump.
I knew a guy that had a 69 GMC PU that he converted to 4x4.
It was an automatic, and he still ran the low hump.

I just fit my 67 with a 4L60E and an NP208. They fit with about an inch of clearance under a low hump floor in the tightest clearance areas. Don't know if the transfer case shifter is going to fit yet or not through.

Zeke · 09-24-2010, 05:23 AM

If you can't find one locally or from another board member try ECE. They show one in their used parts. Probally worth calling to see if they have one for a manual trans.

http://www.earlyclassic.com/tech.asp...y=Used%20Parts

bsteele · 09-24-2010, 06:47 AM

I found two at pull-a-part a couple of weeks ago.

07-23-2010, 03:11 PM	#1
1968SWBBigBlock Active Member Join Date: Oct 2006 Location: Ohio Posts: 1,643	Low Hump to High Hump conversion Can anyone give me a step by step procedure for replacing the low hump with a high hump in my 68? __________________ 1968 SWB 454 + .040, 490HP x 540 FT pounds of Torque 10-1 Kb Forged pistons, recon rods w/ ARP wave loc bolts 781 heads Ported with 2.19/1.88 SSTvalves Lunati 60204 cam, Micro Trol lifters, Ported Edelbrock Performer Rpm manifold armor coated, Pertronix Triple Strike Ignition Holley 770 Street Avenger carb,Headers armor coated Built by Watson Ruppel Performance in Sarahsville Ohio. Hardshift Tranny Built Turbo 350,TSI 10" 3000 stall 12 Bolt Eaton Posi 4.10 Richmond Gears moser axles 18.5" x 31" Hoosier Pro Street Radials ET Classic 5 Wheels - polished Power Steering, Power Brakes,Disc Brakes,Tach & Gauge Dash, Tilt,Factory Air (gone) Custom Paint & Body Work Special thanks to my wife, my son and my money tree

07-23-2010, 03:49 PM	#2
gregg72340 Registered User Join Date: May 2010 Location: ambler, pa Posts: 325	Re: Low Hump to High Hump conversion Bump I need it too __________________ Just would like the snow to stop so I can actually work on my truck!!!!!!!!!!!

07-23-2010, 04:00 PM	#3
redbaron69 Registered User Join Date: Jan 2009 Location: marion nc Posts: 588	Re: Low Hump to High Hump conversion me three... is the high hump a must have if you put in a big block? or is it the trans you use? __________________ 69 short fleet 350/350 "under construction" 70 short step 307/3 speed

07-23-2010, 04:42 PM	#4
Sammy Registered User Join Date: Apr 2000 Location: Bonne Terre, Mo Posts: 3,005	Re: Low Hump to High Hump conversion Been awhile (15 yrs) since I done mine but sure someone will add to it. Remove the seat, carpet/ or mat and any thing on the floor for access. Carefully mark the floor with chalk for cutout. Remove anything under the floor ie D/S and tranny. Cut out the area with a torch / plasma cutter staying within the area you marked. Install the high hump and put your new mat or carpet in and seat. If your putting a tranny shift thru the floor you can install the high hump cover after the tranny. __________________ '69 Chevy Long Fleet & '71 GMC Short Step & Project "ODD BALL" "You can wash a pig, soak it in most expensive perfume. In the end it is still just a pig." ODD BALL build thread http://67-72chevytrucks.com/vboard/s...d.php?t=478629"

07-23-2010, 09:28 PM	#5
gregg72340 Registered User Join Date: May 2010 Location: ambler, pa Posts: 325	Re: Low Hump to High Hump conversion From what I have heard on here you need the high hump for the big block __________________ Just would like the snow to stop so I can actually work on my truck!!!!!!!!!!!

07-23-2010, 10:03 PM	#6
Sammy Registered User Join Date: Apr 2000 Location: Bonne Terre, Mo Posts: 3,005	Re: Low Hump to High Hump conversion To hold the hump down since my cab was still installed I used some 1/2" or 7/16" diameter self tapping bolts, w/ washer and a small bit to pre-drill my location. __________________ '69 Chevy Long Fleet & '71 GMC Short Step & Project "ODD BALL" "You can wash a pig, soak it in most expensive perfume. In the end it is still just a pig." ODD BALL build thread http://67-72chevytrucks.com/vboard/s...d.php?t=478629"

07-24-2010, 01:29 AM	#8
60ratrod yes, i do Join Date: Jun 2007 Location: Spokane, wa Posts: 2,734	Re: Low Hump to High Hump conversion pretty much the only reason to go high hump is if you are switching from a th350(2wd) or the 3 on the tree(2wd). i don't remember if the 4wd versions needed the high hump or not. but the size of the popular saginaw and muncie 4 speeds as well as the th400 required the extra clearance. that's why when i swap cabs on my 72 i'm gonna look for a 4-5 speed that doesn't require the high hump and will allow me to use the stock 2 piece shaft __________________ ERROR 404....... SNAPPY COMEBACK NOT FOUND _______________________________________________________________________________________________ -60 Chevy C10, dead 350/good th350 combo, sitting on a 76 c10 blazer frame, built from 11 different vehicles "the abomination" -07 gmt900 silverado 1500 lt xcab z71, granite blue -81 suzuki gs650g "shelah"- current project -81 kz1000m1 csr "sarge" -next project (just beautification) -07 kawasaki vulcan classic vn900

07-24-2010, 05:07 PM	#9
redbaron69 Registered User Join Date: Jan 2009 Location: marion nc Posts: 588	Re: Low Hump to High Hump conversion good info on the trans part guys. if that the case i just keep my low hump and run a th350. thanks __________________ 69 short fleet 350/350 "under construction" 70 short step 307/3 speed

07-24-2010, 06:14 PM	#10
leddzepp Moderator Join Date: May 2007 Location: Southern Cal Posts: 19,997	Re: Low Hump to High Hump conversion I have seen trucks with a BBC/TH400 with a low hump cab. __________________ 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

07-24-2010, 06:28 PM	#11
vectorit What? Join Date: Jun 2007 Location: Southern California Posts: 7,617	Re: Low Hump to High Hump conversion I know that on my burb with its high hump, while running an sm465 trans I could not run a low hump if I wanted to. The t-case is behind the hump, but the shifter bracket pokes through the high hump. I knew a guy that had a 69 GMC PU that he converted to 4x4. It was an automatic, and he still ran the low hump. __________________ Chris 1968 K20 Suburban 1972 K10 LWB PU

07-24-2010, 06:58 PM	#12
1-PU70 Registered User Join Date: Apr 2000 Location: Bradenton, FL Posts: 1,036	Re: Low Hump to High Hump conversion Im running a 402 with a 700R4 in a low hump. __________________ 1970 CST/10 402,700R4,3:73 posi,AC,PS,PB,TLT,PW,Buckets with heaters

07-24-2010, 07:47 PM	#13
haysonj Registered User Join Date: Dec 2007 Location: Santa Maria, Ca. Posts: 1,423	Re: Low Hump to High Hump conversion It all depends on how you want to set your motor. I have a 383, T400,208 transfer case, and a Gear Vendors OD all in a low hump C10 converted to a 3/4 ton 4x4. __________________ 69 Chevy 4x4 383 Power

07-25-2010, 08:43 AM	#14
Zeke Active Member Join Date: Jun 2002 Location: L.A. Lower Alabama Posts: 453	Re: Low Hump to High Hump conversion Someone correct me if I am wrong but they way I see it with the standard 4sp they put the high hump in there so you could get to the top cap just in case you needed to inspect the gears or change shifter balls so you wouldn't have to drop the tranny. If I remember those things weigh a ton. As far as other trucks with different engine transmission combos it was probably a money thing, its cheaper to make a cover than a different floor, if a truck was going down the line and a change was made or they didn't have low hump floor it got a high hump. Thats why you see trucks with the same engine/trans combo some with low and some with high humps. Just my thinking, might be wrong though. __________________ 1969 C10 350 3spd 1995 GMC 3500 XC 350 dually When Thomas Edison worked late into the night on the electric light, he had to do it by gas lamp or candle. I'm sure it made the work seem that much more urgent. George Carlin

09-07-2010, 02:56 PM	#15
codeJbird Registered User Join Date: Nov 2009 Location: Roanoke, LA Posts: 101	Re: Low Hump to High Hump conversion i've already cut out part of my floor for my tranny and i can't seem to find a 4x4 high hump anywhere. more like i'm looking in the wrong spot. i was told that it is a bolt in replacement. __________________ Bird

09-23-2010, 05:25 PM	#16
codeJbird Registered User Join Date: Nov 2009 Location: Roanoke, LA Posts: 101	Re: Low Hump to High Hump conversion anyone know where to find the high hump or 4x4 transmission tunnel for a replacement? thnx, bird __________________ Bird



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09-24-2010, 05:23 AM	#18
Zeke Active Member Join Date: Jun 2002 Location: L.A. Lower Alabama Posts: 453	Re: Low Hump to High Hump conversion If you can't find one locally or from another board member try ECE. They show one in their used parts. Probally worth calling to see if they have one for a manual trans. http://www.earlyclassic.com/tech.asp...y=Used%20Parts __________________ 1969 C10 350 3spd 1995 GMC 3500 XC 350 dually When Thomas Edison worked late into the night on the electric light, he had to do it by gas lamp or candle. I'm sure it made the work seem that much more urgent. George Carlin

09-24-2010, 06:47 AM	#19
bsteele Registered User Join Date: Feb 2009 Location: Kershaw, South Carolina Posts: 113	Re: Low Hump to High Hump conversion I found two at pull-a-part a couple of weeks ago.

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