High or low Trans hump - The 1947 - Present Chevrolet & GMC Truck Message Board Network

**OneBad71** · 08-23-2023, 12:04 PM

I may have screwed up again on my 71 C10 project ? I am getting close to having the cab painted and here's the question.
My truck came with a 350, with TH350 trans.
I installed a 496 BB with a TH400 Trans.
My truck has the low hump (factory)
Will everything fit or do I have to now add the high hump to my floor ?
Time is limited but I don't want to get everything painted and find out the cab hits the trans.
Please let me know what others have or have done,
Thank you,
Dan

Rich72C10 · 08-23-2023, 12:32 PM

not that I know directly but this poster says: "I got the big block stands and put a bbc in a low hump with a t400 with no problems"

I think I read before that poster the high hump was for manual transmissions - again not that I directly know.

72c20customcamper · 08-23-2023, 01:07 PM

My 68 Anniversary has the TH400 with the low hump engine should have no bearing

57taskforce · 08-23-2023, 01:45 PM

Most but probably not all TH400’s had a high hump and all 4speed and 4x4 trucks definitely did.

**OneBad71** · 08-23-2023, 06:27 PM

Thanks for the above replies.
I'm on the fence on what to do ? It would be easier if needed to do it now before paint. Not that I want to cut the floor, but after paint and it sitting on the frame will cause a lot more work.
Hopefully we can get more people who have done what i'm trying to do to chime in on their experience .
Maybe some trucks just had more room than others ?
With the tubular engine mounts I did mount them in the forward bolt hole.
I think that's what all the BB's have to do ?
I totally appreciate all the help !
Dan

ZEKE68 · 08-23-2023, 08:03 PM

I put a 454 big block with a 4L80E automatic into my 68 short stepside with a low hump. I had bought a high hump to install when I started the project, but I never installed it. I had installed a 2 cup cup holder to the front of my bench seat and didn't want to give it up, so I tried it with the low hump. It all worked out ok, but it would have been nice to have more room when I was trying to dial in the drive shaft angles. I had to shim under the rear trans mount until I was only about 3/4" below the pan, and I still had to add taper shims to the rear axle mounts to get the u-joint angles close enough. Because my truck is lowered it made all this worse, because it moves the rear end, drive shaft, and trans rear up higher to be aligned. You can make it work with the low hump, but if it doesn't matter to you if the hump is higher inside the cab, then install the high hump.

**OneBad71** · 08-23-2023, 08:58 PM

Quote:

Originally Posted by ZEKE68

I put a 454 big block with a 4L80E automatic into my 68 short stepside with a low hump. I had bought a high hump to install when I started the project, but I never installed it. I had installed a 2 cup cup holder to the front of my bench seat and didn't want to give it up, so I tried it with the low hump. It all worked out ok, but it would have been nice to have more room when I was trying to dial in the drive shaft angles. I had to shim under the rear trans mount until I was only about 3/4" below the pan, and I still had to add taper shims to the rear axle mounts to get the u-joint angles close enough. Because my truck is lowered it made all this worse, because it moves the rear end, drive shaft, and trans rear up higher to be aligned. You can make it work with the low hump, but if it doesn't matter to you if the hump is higher inside the cab, then install the high hump.

Thanks for the info. That's kind of where i'm at. Just installing the high hump, which looks pretty straight forward and not loosing any sleep or headaches later. The AMD panel was only like $100 so it basically my time and some tools. Dan

3767 · 08-23-2023, 09:11 PM

If you are staying at or near the stock height, then the low hump will work. If you are dropping the body down or it’s on your to do list some day,then the high hump. With the high hump you also have the option to install something like a 6l80 down the road with the room the high hump provides. Same goes for a change to a manual if that’s in the cards for you.

**kwmech** · 08-24-2023, 12:19 AM

With decent body mounts and a low hump there should still be room to get your hand around the 2. I can on my 69, it's snug, but there is room

**1970 CST Short Wide** · 08-24-2023, 12:31 AM

When my truck had the 454 the factory low hump worked fine but I had a 350 TH. When I swapped in the LS and T56 six speed I had to put in the high hump. Look at this way, putting in a high hump is an easy thing to do. Down side is you need different carpet but it sounds like your not at that point yet so not an issue. Long story short going with a high hump won’t hurt anything
And you’ll have more room if needed

**OneBad71** · 08-24-2023, 01:02 PM

Quote:

Originally Posted by 3767

If you are staying at or near the stock height, then the low hump will work. If you are dropping the body down or it’s on your to do list some day,then the high hump. With the high hump you also have the option to install something like a 6l80 down the road with the room the high hump provides. Same goes for a change to a manual if that’s in the cards for you.

Thanks for replying. I figure it's worth the time to just had the high hump and be done with it.

**OneBad71** · 08-24-2023, 01:03 PM

Quote:

Originally Posted by 1970 CST Short Wide

When my truck had the 454 the factory low hump worked fine but I had a 350 TH. When I swapped in the LS and T56 six speed I had to put in the high hump. Look at this way, putting in a high hump is an easy thing to do. Down side is you need different carpet but it sounds like your not at that point yet so not an issue. Long story short going with a high hump won’t hurt anything
And you’ll have more room if needed

Thanks for the input. That's what I was thinking just do it and i'm covered for most anything in the future.

**OneBad71** · 08-24-2023, 05:26 PM

Hello, I just wanted to reach out and thank everyone who shared some input in my project.
I cut out the low hump today using a air mini sawzall and my angle grinder with a flapper disc and it turned out super clean and really wasn't difficult to do.
GM made it easy by stamping the floor to give you a guide and where to cut.
Next, I'll seal and bolt it down and it's done.
Thanks again, Dan

**yote1234** · 09-02-2023, 01:21 PM

Quote:

Originally Posted by OneBad71

Hello, I just wanted to reach out and thank everyone who shared some input in my project.
I cut out the low hump today using a air mini sawzall and my angle grinder with a flapper disc and it turned out super clean and really wasn't difficult to do.
GM made it easy by stamping the floor to give you a guide and where to cut.
Next, I'll seal and bolt it down and it's done.
Thanks again, Dan

i think you made a good choice

**OneBad71** · 09-02-2023, 04:03 PM

Quote:

Originally Posted by yote1234

i think you made a good choice

Thanks, I do too.

68Gold/white · 09-02-2023, 07:22 PM

My 68 Anniversary 396/TH400 has the high hump. I also have a 67 C10. It came with a 283 and glide. It has the low hump. I plan to install a high hump in it, mostly because the high hump is bolted in. ANY work in that area can be made easier by removing the high hump (God forbid...).

08-23-2023, 12:04 PM	#1
OneBad71 Junior Member Join Date: Jul 2022 Location: Gardnerville Posts: 70	High or low Trans hump I may have screwed up again on my 71 C10 project ? I am getting close to having the cab painted and here's the question. My truck came with a 350, with TH350 trans. I installed a 496 BB with a TH400 Trans. My truck has the low hump (factory) Will everything fit or do I have to now add the high hump to my floor ? Time is limited but I don't want to get everything painted and find out the cab hits the trans. Please let me know what others have or have done, Thank you, Dan

08-23-2023, 12:32 PM	#2
Rich72C10 Mr. Cheyenne Join Date: Jun 2020 Location: Kyle, Texas Posts: 1,688	Re: High or low Trans hump not that I know directly but this poster says: "I got the big block stands and put a bbc in a low hump with a t400 with no problems" I think I read before that poster the high hump was for manual transmissions - again not that I directly know. __________________ Richard *'72 Chevy C10 Cheyenne Super WHT/MED BRONZE/WHT SBC 350 \| TH350 \| LWB \| AC \| Buddy Seats Upgrades:** Tilt \| Front Sway Bar \| Radio \| Sliding Window \| Bed Spare w/Lock Bed Rails \| Full LEDs \| Courtesy Lights \| Tachometer \| Glovebox Lock & Light \| Head Light Relays \| *Upgraded Fully Super Trim

08-23-2023, 01:07 PM	#3
72c20customcamper Registered User Join Date: Jul 2018 Location: Catskill Mountains,NY Posts: 8,500	Re: High or low Trans hump My 68 Anniversary has the TH400 with the low hump engine should have no bearing __________________ Mark 72 c20 custom camper Husky edition, 66 SS396 Chevelle 1964 Hawk, 63 Avanti,62 lark 1969 AMX , 1968 c20 stepside ,85 K20 1977 Suburban sold 68 anniversary.

08-23-2023, 01:45 PM	#4
57taskforce All about them K’s Join Date: Jun 2014 Location: Land of Entrapment Posts: 6,393	Re: High or low Trans hump Most but probably not all TH400’s had a high hump and all 4speed and 4x4 trucks definitely did. __________________ Tyler '57 3100 http://67-72chevytrucks.com/vboard/s...d.php?t=813888 '72 K20 Cheyenne: 5” lift, 35’s, front dana 60 blah blah blah… http://67-72chevytrucks.com/vboard/s...d.php?t=662879 ‘69 K10 SWB: 4” lift 33”s… in a million pieces http://67-72chevytrucks.com/vboard/s...d.php?t=805206 '98 Silverado LT K2500HD ECLB Vortec 454/4l80E: 6" lift 315/75/16's Last edited by 57taskforce; 08-23-2023 at 01:52 PM.

08-23-2023, 06:27 PM	#5
OneBad71 Junior Member Join Date: Jul 2022 Location: Gardnerville Posts: 70	Re: High or low Trans hump Thanks for the above replies. I'm on the fence on what to do ? It would be easier if needed to do it now before paint. Not that I want to cut the floor, but after paint and it sitting on the frame will cause a lot more work. Hopefully we can get more people who have done what i'm trying to do to chime in on their experience . Maybe some trucks just had more room than others ? With the tubular engine mounts I did mount them in the forward bolt hole. I think that's what all the BB's have to do ? I totally appreciate all the help ! Dan

08-23-2023, 08:03 PM	#6
ZEKE68 Registered User Join Date: Jul 2012 Location: Space Coast, Florida Posts: 403	Re: High or low Trans hump I put a 454 big block with a 4L80E automatic into my 68 short stepside with a low hump. I had bought a high hump to install when I started the project, but I never installed it. I had installed a 2 cup cup holder to the front of my bench seat and didn't want to give it up, so I tried it with the low hump. It all worked out ok, but it would have been nice to have more room when I was trying to dial in the drive shaft angles. I had to shim under the rear trans mount until I was only about 3/4" below the pan, and I still had to add taper shims to the rear axle mounts to get the u-joint angles close enough. Because my truck is lowered it made all this worse, because it moves the rear end, drive shaft, and trans rear up higher to be aligned. You can make it work with the low hump, but if it doesn't matter to you if the hump is higher inside the cab, then install the high hump. __________________ 1968 SWB Step Side, Big Block, 4L80E , Running!

08-23-2023, 09:11 PM	#8
3767 Registered User Join Date: Aug 2019 Location: Vale,nc Posts: 169	Re: High or low Trans hump If you are staying at or near the stock height, then the low hump will work. If you are dropping the body down or it’s on your to do list some day,then the high hump. With the high hump you also have the option to install something like a 6l80 down the road with the room the high hump provides. Same goes for a change to a manual if that’s in the cards for you.

08-24-2023, 12:19 AM	#9
kwmech Senior Member Join Date: Mar 2003 Location: Colfax-California Posts: 8,550	Re: High or low Trans hump With decent body mounts and a low hump there should still be room to get your hand around the 2. I can on my 69, it's snug, but there is room

08-24-2023, 12:31 AM	#10
1970 CST Short Wide Senior Moment Join Date: Mar 2002 Location: Pittsburg Ca Posts: 4,139	Re: High or low Trans hump When my truck had the 454 the factory low hump worked fine but I had a 350 TH. When I swapped in the LS and T56 six speed I had to put in the high hump. Look at this way, putting in a high hump is an easy thing to do. Down side is you need different carpet but it sounds like your not at that point yet so not an issue. Long story short going with a high hump won’t hurt anything And you’ll have more room if needed __________________ 1970 CST LS 1 6 speed Ford 9 inch Detroit Tru Track, Dakota Didgital, Vintage Air, QA1 Coil Overs Front & Rear Lots of FUN 2013 GMC PU, Oldest Son 71 GMC LWB. QA1 Suspension, Angry SB. Youngest Son 2019 GMC Diesil Dually. Youngest Son 2017 Toyota SUV Daughters car 2018 Traverse , Wife’s Ride Pittsburg Ca 94565 Last edited by 1970 CST Short Wide; 08-24-2023 at 11:19 AM.

08-24-2023, 05:26 PM	#13
OneBad71 Junior Member Join Date: Jul 2022 Location: Gardnerville Posts: 70	Re: High or low Trans hump Hello, I just wanted to reach out and thank everyone who shared some input in my project. I cut out the low hump today using a air mini sawzall and my angle grinder with a flapper disc and it turned out super clean and really wasn't difficult to do. GM made it easy by stamping the floor to give you a guide and where to cut. Next, I'll seal and bolt it down and it's done. Thanks again, Dan

09-02-2023, 07:22 PM	#16
68Gold/white Registered User Join Date: Sep 2011 Location: Ark City, Kansas Posts: 3,337	Re: High or low Trans hump My 68 Anniversary 396/TH400 has the high hump. I also have a 67 C10. It came with a 283 and glide. It has the low hump. I plan to install a high hump in it, mostly because the high hump is bolted in. ANY work in that area can be made easier by removing the high hump (God forbid...).



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