Changing from a Low Hump to a High Hump

[ChevyRacefan]

Book marking just for the vendor info.
I will be adding holes in the firewall, and add plugs, while there to get to the upper bolts of the transmission bell housing. So if the Transmission needs to be pulled ) in my case most likely will be in and out a bunch) It just be a matter of pull the 4 grommit plugs . and socket and ex. to get to the bolts. Getting to them when vehicles are on stands is a pain. this will make it simple. and might as well add them while there adding the hump.
Making swapping/testing converters at the track a lot easier.

[Gary 70 Jimmy]

Good information I will be cutting mine out to.

[3757chevy]

Originally Posted by 3757chevy

QUOTE:
Re: 72 one piece high hump cab floor
The big blocks with turbo 400 were high hump. The small blocks with th400 were low hump.:Quote......................................................................................... .................................................................................................... .................................................................................................... ........................... I stand corrected.

I bought a '68 Suburban last June 327 w/TH400 and a low hump.

[kwmech]

Originally Posted by 3757chevy

QUOTE:
Re: 72 one piece high hump cab floor
The big blocks with turbo 400 were high hump. The small blocks with th400 were low hump.:Quote......................................................................................... .................................................................................................... .................................................................................................... ........................... I stand corrected.

Which begs the question--- if that is true-- WHY?? the placement of the big block engine moves the transmission forward 1-1/2'' giving more room around the hump. My 69 1 ton originally had a 350. I converted to a 454 and had to move the trans x-member and linkage pivot forward. Still a low hump with more clearance. I can get my fat hand all around the trans case

[CC69Rat]

Just noticed this one, I know it's an older post but just adding to Dads comments.

This truck had quite a few modifications to the Kmember, engine mounts, etc. It was done before I bought it. The engine had been moved back from the factory location (Big Block, or small block) to help keep it from plowing in the corners. With the BBC setup it was done this way to keep it from being nose heavy. It definitely wasn't in the stock Fore/ Aft position.

I understand it can be done with a low hump. Just saying, in this truck, in this position we had to do a high hump to get it to clear.

Just wanted to clarify. Pop was really just trying to document how it's done, where to cut, how we did it, etc. Not saying you need a high hump if you have a TH400.

[CC69Rat]

Originally Posted by kwmech

... the STOCK placement of the big block engine moves the transmission forward 1-1/2'' giving more room around the hump. .. This truck wasnt in the stock mount position.

[kwmech]

Originally Posted by CC69Rat

Either way there is still clearance for the automatic. SM465 4 speed, with or without t-case......nope

[georgieb51]

Originally Posted by gmc684x4

My understanding trucks with t400 came factory with high hump

I did this on my 68 gmc when i went from 2x4 to 4x4 there is a spot welded ring that is below the floor pan for use of bolts not sheetmetal screws to secure high hump pan

Maybe this is getting a little off track but since you brought it up I will report that my 1970 GMC2500 3/4 came stock with the TH400 and a low hump. I had to double check since I recently purchased carpet and had to get the hump right

[Mike C]

I have a ‘69 C2500 parts truck with a first year small block 350 and TH400 and its a high hump. All the big block trucks I have owned have been high hump. Same with SM465.