High humps and low humps: which way is the conversion usually done?

[Brad54]

I got to thinking about this the other day: I usually see the high hump tunnels and the firewall piece for sale, but rarely see the low-hump pieces for sale.
Did I miss it, or do most of the trans tunnel conversions go from low hump to installing a high hump?

Does the low hump clear a modern auto trans?
Why do most guys install the high humps? My suburban came with the high hump and a 4spd granny, and my k20 came with a high hump but a 3spd manual on the column.

OR, do I have it backwards, and guys install the low humps in place of the high humps?

(And while I'm at it, what year did they change from bolt-in to a welded in piece of the floor?)
-Brad
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[The Rocknrod]

I have a 200R4 with a 350 set up in a low hump cab, so I don't know for sure why. Maybe the LS guys need it.

[Joemomma1]

From what I've seen it's low to high than people are after. It may be for clearance issues but I don't fire sure know why people do it. My truck had the high hump but our low hump truck fits a auto tranny just fine.

[pestwagon]

Low humps were for AT trucks. They are rarer than 3 and 4 speed trucks. So in junkyards if you want to convert to a low hump floor from a original 4 speed high hump I looked at a lot of trucks this year before I found a good low hump floor to use.

I think the guys slamming theire trucks down with air ride might want the high humps for clearences.

[Joemomma1]

Originally Posted by pestwagon

Low humps were for AT trucks. They are rarer than 3 and 4 speed trucks. So in junkyards if you want to convert to a low hump floor from a original 4 speed high hump I looked at a lot of trucks this year before I found a good low hump floor to use.

I think the guys slamming theire trucks down with air ride might want the high humps for clearences.

We've had and seen plenty of tree shifting trucks with low hump. So it's probably not exclusive to the auto trucks

[66ChevyMax]

My truck was originally a 3 on the tree with low hump!

[aerotruk63]

The low hump was for Auto and 3 Speed Manual.
4 speed manual had the High Hump.

In some years on the Medium Duty trucks the the front section was also removable.
1963 C60 shown.

[theastronaut]

I'm building a bagged '66 and need to swap to a high hump to clear the T56 six speed.

[scoot_mcgrute]

Originally Posted by theastronaut

I'm building a bagged '66 and need to swap to a high hump to clear the T56 six speed.

Do you need the high hump to clear the T56 because you are bagging it or does it look like a more conventional setup need a high hump as well?

[theastronaut]

I believe you can barely stuff in a T56 under a low hump floor if you're stock height or doing a static drop. I have mine mocked up and the low hump is holding the cab from dropping all the way down when it's aired out.

[LVPhotos]

My 1962 came v8 3 on tree, small hump. First cut was floor shift conversion, 2nd my hack to fit T5 (didn't have weld skills or machine ) 3rd was high hump for TKO 600 and PORTERBUILT up and forward movement. And yes my low hump was bolt in.

[andyh1956]

Has anyone changed from a low hump to a high hump & bolted the front section of the high hump in? I'm gonna be using an NV4500 trans & thought it might be an advantage down the road sometime to have it bolted in.

[66Submarine]

Originally Posted by andyh1956

Has anyone changed from a low hump to a high hump & bolted the front section of the high hump in? I'm gonna be using an NV4500 trans & thought it might be an advantage down the road sometime to have it bolted in.

http://www.6066gmcguy.com/3-to-4-speed.html

Kind of. My hands are bleeding just thinking of all the sheet metal screws! Don't see any reason you can't bolt it in if you want to.

Are you going to use the NV4500 bellhousing?

[Blue666(2)]

I went from a low hump to high hump because I liked the look better. My A833 trans fit with tight clearance under the low but I liked the look of the high hump.

[andyh1956]

Originally Posted by 66Submarine

http://www.6066gmcguy.com/3-to-4-speed.html

Kind of. My hands are bleeding just thinking of all the sheet metal screws! Don't see any reason you can't bolt it in if you want to.

Are you going to use the NV4500 bellhousing?

No I am gonna spring for the Advance Adapters housing that puts the clutch linkage on the driver's side because mine is 4WD.
If I bolt the front section down I will weld nuts on the bottom just like the rear section is fastened, I don't like those pointy sheet metal screws either!

[Cricket59]

The high humps were mostly needed for the Big Block motors with 400TH

[Captainfab]

I have a big block & TH400 in my '66 Suburban with a low hump.

Originally Posted by Cricket59

The high humps were mostly needed for the Big Block motors with 400TH

['63GENIII]

Originally Posted by Captainfab

I have a big block & TH400 in my '66 Suburban with a low hump.

^^^ This. With the NV4500, I needed the high hump. When I had the 400 in it, I could have fit another transmission between the 400 and the tunnel..... well not really but there was a lot more room though. Not so much with the manual trans now.

[nsb29]

I had to go to a high hump with my LS swap to clear the 6L80 trans

[nsb29]

Originally Posted by theastronaut

I believe you can barely stuff in a T56 under a low hump floor if you're stock height or doing a static drop. I have mine mocked up and the low hump is holding the cab from dropping all the way down when it's aired out.

I got a dum question how does dropping the truck Change Transmission clearance is it because you have raised the transmission for ground clearance

[nsb29]

I had to go to a high hump with my LS swap to clear the 6L80 trans

[lilpoindexter]

I like the low hump look. My 63 3ott had the low hump factory. Even if i have to have a 4L60 instead of a 4L80 or whatever i would do it, since i want the low hump.