3 speed vs 4 Speed trans hump? (1 Viewer)

[Ron Rico]

My 1971, 40 series has a 3speed. The transmission and transfer case shifters are on the floor. The truck was incomplete when I purchased it.

Among other things, I am missing the Transmission hump AND a section of the driver side floor pan under the seat or where the tool box would have been. A previous owner cut out the floor all the way to the trans-hump cutout so I’d like to get a hump and have it on hand in order to create the floor.

MY QUESTIONS : in my hunt for a trans hump can I use either a 3 speed or 4 speed hump cover? DOES IT MATTER?

ARE THE FLOOR CONTOURS AND BOLT HOLES THE SAME for the 3 speed and 4 speed hump?

the truck has a body lift so clearance or hump height is a non issue.

at this point Ive decided to just get a fiberglass hump because the sheet metal used hump hunt only produces junk.

does it matter which trans hump I order?

When I look at pictures, the 3speed seems to have an arched contour at the rear and doesn't have a flat flange at the rear like the 4spd.

the 4speed SEEMS the same contours and shape, and it also has a flat flange all the way around that matches the contour of my floor which is flat at the rear of the the trans hump floor cut out… NOT arched.

Basically Im considering strongly getting a 4 speed cover - is there something Im missing as to why that won't bolt up with the floor? I’m not as concerned where the shifters poke out as I am the the floor to hump mating up properly.

Do the Factory bolt holes all line up/ match up with either?

If the gasket kit from SOR is the same for either you'd think the holes match up either way.

Help. I’m really ready to get the floor and seats in !!!

 

[lcwizard]

They are not interchangeable without some pretty involved body work.

 

[73FJ40]

It looks to me like you have a '73 and later torque tube. It's the cylindrical cross member that goes above the rear drive shaft. Is it possible a PO changed out the tube , or even the whole frame? I would check the tube for butt welds inside the frame rails. If no butt welds, I'd look at the frame no. on the outside of the right front frame rail, just behind the bumper stays.

The pre '73 hump fit up to a "bump" in the tub, much different than later humps. I don't see that bump in you pic, but maybe the hump is long gone with the rest of the floor

The bolt pattern for my '73 three speed hump was identical to the four speed hump, but note that there were revisions in the 73 model that were in preparation for upgrading to the four speed.

The fiberglass hump from SOR has indentations in the flange that line up with their gasket pieces; but the fiberglass part isn't as perfect as the OEM steel stamping, so some of the holes in the hump may not line up perfectly and may need to be egged out.

 

[65swb45]

IMHO, the uncut 4speed fiberglass hump would be ideal for your situation.

www.marksoffroad.net

 

[Ron Rico]

It looks to me like you have a '73 and later torque tube. It's the cylindrical cross member that goes above the rear drive shaft. Is it possible a PO changed out the tube , or even the whole frame? I would check the tube for butt welds inside the frame rails. If no butt welds, I'd look at the frame no. on the outside of the right front frame rail, just behind the bumper stays.

The pre '73 hump fit up to a "bump" in the tub, much different than later humps. I don't see that bump in you pic, but maybe the hump is long gone with the rest of the floor

The bolt pattern for my '73 three speed hump was identical to the four speed hump, but note that there were revisions in the 73 model that were in preparation for upgrading to the four speed.

The fiberglass hump from SOR has indentations in the flange that line up with their gasket pieces; but the fiberglass part isn't as perfect as the OEM steel stamping, so some of the holes in the hump may not line up perfectly and may need to be egged out.

ya know - the motor is a 73...
this theory makes sense and these types of clues/ confusion have thrown me off in a few different area's now. Will check frame and report back.

Im beginning to think someone had a title and tags for a 71 so thus the current title and tags on the fender and door jam but everything seems 73.

the floor is intact at the rear of the trans hump cut out so I'm pretty sure the 4 speed style hump is what I need.

I'M ORDERING THE TRANS HUMP FROM JT CRUISERS - cause they're on the east coast just south of me. Anyone familiar with they're product vs the SOR trans hump that is 2x the money? I'll still order the gasket from SOR just cause can't find it anywhere else. CITYRACER has almost all the body weatherstripping / seals (and good quality for 1/3 the price) but not for the hump.