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Old 02-21-2018, 03:08 PM   #1
SunSoaked
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Hi-Low Hump in late square?

So a thread in the for sale section got me thinking since I'm in the process of swapping a 4500 into my 85 k20 to replace the th400. Do the later squares have a removable hump and is there actually a low & high version? If so, what dictates the high vs low: 2wd/4wd or auto/manual? This was obvious on my 69 but I haven't pulled up the floor mat yet to have a look see.
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Old 02-21-2018, 04:17 PM   #2
Lnielson
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Re: Hi-Low Hump in late square?

I'm swapping a NV4500 in place of a SM465 in my truck right now, 1986 K30 Crew. The 81 and up squares do not have a removeable tunnel. I don't know what dictates the high/low hump changes. I'm going to cut mine and make it removeable.
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Old 02-21-2018, 04:31 PM   #3
SunSoaked
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Re: Hi-Low Hump in late square?

I'm hoping to just cut a hole big enough for the shifter: maybe the shift tower if need be. Cutting out the whole hump would require having another one slightly larger to cover the opening. That's why I was asking about the hi versus low or if it's all the same.
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Old 02-21-2018, 07:56 PM   #4
TKCR
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Re: Hi-Low Hump in late square?

2wd auto trans or 2wd column shift manual = low hump

4wd or any floor shifted manual trans = high hump
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Old 02-21-2018, 10:57 PM   #5
SunSoaked
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Re: Hi-Low Hump in late square?

TKCR- To the rescue as usual. Thank you for the clarification.
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Old 02-22-2018, 07:25 AM   #6
echo7bravo
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Re: Hi-Low Hump in late square?

Quote:
Originally Posted by SunSoaked View Post
So a thread in the for sale section got me thinking since I'm in the process of swapping a 4500 into my 85 k20 to replace the th400. Do the later squares have a removable hump and is there actually a low & high version? If so, what dictates the high vs low: 2wd/4wd or auto/manual? This was obvious on my 69 but I haven't pulled up the floor mat yet to have a look see.
I'm in the process of doing a cab swap on my '86 4WD. I am using a '79 2WD cab due to it being completely rust free and readily available.

I was contemplating cutting the hump out of my '86 and welding into the '79 to get the higher hump. But I have been told that there should be enough clearance for the bell housing. I think the high humps were designed to raise the shifters up closer to the driver. Whether it was the manual shift or a transfer shifter.

So as for converting your automatic to manuall....the only think that I know of is that your shifter will set a couple inces lower and may not be as comfortable to shift. Could get a longer shift stick, but that would create a longer throw. All personal preference that I can see. But should all fit.
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Old 02-22-2018, 09:53 AM   #7
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Re: Hi-Low Hump in late square?

73-80 have 2 different high humps...2wd and 4wd. Also, the floors are different at the rear of the high humps. The 4wd floors are higher than the 2wd where the removable hump meets the floor under the seat. 81-83 are bolt in high humps. 84 and newer are NOT bolt in.
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Old 02-22-2018, 09:54 AM   #8
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Re: Hi-Low Hump in late square?

Quote:
Originally Posted by echo7bravo View Post
I'm in the process of doing a cab swap on my '86 4WD. I am using a '79 2WD cab due to it being completely rust free and readily available.

I was contemplating cutting the hump out of my '86 and welding into the '79 to get the higher hump. But I have been told that there should be enough clearance for the bell housing. I think the high humps were designed to raise the shifters up closer to the driver. Whether it was the manual shift or a transfer shifter.

So as for converting your automatic to manuall....the only think that I know of is that your shifter will set a couple inces lower and may not be as comfortable to shift. Could get a longer shift stick, but that would create a longer throw. All personal preference that I can see. But should all fit.
Not trying to offend here, but none of this is correct. A manual trans will not fit inside the low hump, especially an NV4500. The height of the hump has no impact on the height of the transmission shifter. The shifter is directly attached to the top of the transmission, not the floorboard. What you said is true about the transfer case shifter, but not the transmission.

What TKCR said is correct about the high hump vs low hump for the 81-up trucks. I used a bolt in high hump from a 73-80 4wd truck when I swapped my 2WD Suburban to an NV4500. It took some serious hammering to fit the later floorboard (the floorboard seems to have changed shape a good bit when they got rid of the bolt in hump), but it eventually fit pretty well. There's a lot of photos of it in my NV4500 swap thread: http://www.67-72chevytrucks.com/vboa...d.php?t=610659 (scroll to post #17 for the re-uploaded photos)

Just to reiterate, there's no way a NV4500 will fit without either using the 4x4/manual trans high hump, or installing a serious body lift. The photo below is a pretty good representation of how high an NV4500 sits relative to the rest of the floorboard:



SunSoaked, you're good because your K20 already has the high hump. echo7bravo is going to need some mods to clear a manual trans in his swap.
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Old 02-22-2018, 09:54 AM   #9
RADustin
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Re: Hi-Low Hump in late square?

for the early trucks at least there are two different high humps. A 4x4 and 2wd manual trans.

see attached.
Attached Images
File Type: pdf 73-87 Trans Tunnels1.pdf (236.1 KB, 13 views)
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Old 02-22-2018, 09:55 AM   #10
cal30_sniper
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Re: Hi-Low Hump in late square?

Quote:
Originally Posted by KrazyRay View Post
73-80 have 2 different high humps...2wd and 4wd. Also, the floors are different at the rear of the high humps. The 4wd floors are higher than the 2wd where the removable hump meets the floor under the seat. 81-83 are bolt in high humps. 84 and newer are NOT bolt in.
I didn't know that about the different earlier high humps. That explains why mine took so much hammering at the rear to fit.
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Old 02-22-2018, 10:06 AM   #11
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Iím no expert. Trying to figure things out myself. Only Iím not dealing with manual trans. Iím just trying to cab swap a rust free cab onto my 4wd. I think I am still going to have to cut and replace my hump with the one from my original cab if I canít get away with a 1Ē body lift.
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