Floor Pan - High Hump vs. Low Hump?

[FloridaPhil]

My 1968 Ranger 2WD came with a 360 V8 and a three speed column shift manual transmission. I am changing the truck over to a C6 automatic. I search this forum and there are posts saying I need a removable cover high hump transmission tunnel for the C6. Can I buy a removable cover (salvage yard or EBay), cut out my low hump to make clearance for the C6? Any other issues I need to worry about? Thanks!

[flyboy2610]

The C6 and 4 speeds used the high hump, while the 3 on the trees used the low hump, so yes you could have a clearance problem. How bad it is I'll have to leave to someone who has done the same swap.

[Racer Z]

At rest it might seem to clear OK. Keep in mind that under load the motor/tranny moves a bit in the rubber mounts. Don't need no CLUNK on acceleration / deceleration or every time the tranny shifts.

[basketcase0302]

Phil,
I threw a C-6 in mine a year or so ago but have forgotten if I put the low or high hump in. Maybe look through my pics and it might tell? The covers are still pretty common so a boneyard or evilboy should turn up which ever one your looking for.

[colnago]

Ah, that would be why the online companies ask you to specify your transmission when ordering a carpet kit or floor mat. That makes sense now ...

Joseph

[FloridaPhil]

I just found a high hump on EBay. From the posts, I assume all I need to do is cut the floor around the low hump outline then bolt the high hump to the floor. Is that right?

[SVT522]

I ran a C6 behind a 351C in my '67 with a low hump and it cleared with no mods to the floor.

[SVT522]

I ran a C6 behind a 351C in my '67 with a low hump and it cleared with no mods to the floor. Also, the C6 that's behind my current 429 "CJ" clears with no issues.

[FloridaPhil]

Interesting. I'm thinking the low hump floor might be OK for a street driven vehicle. I bought the high hump anyway just in case. Thanks!

[snake]

I was just getting on here to post a similar question about the floor hump and if its required for the C6. I'm just getting started on my swap project where I'm replacing the original fmx with C6(both FEs) and as I'm rolling around under the truck this morning I noticed it doesn't have the cutout/bolt on hump in the floor. So my question was also if the hump is actually necessary for the C6 or just makes installation easier....

I wasn't planning on pulling the seat and replacing the carpet but if I have to, I guess I will.... C6 is already rebuilt and ready for installation....

Thank for the help!

[Racer Z]

I just found a high hump on EBay. From the posts, I assume all I need to do is cut the floor around the low hump outline then bolt the high hump to the floor. Is that right?

Correct. There are a few bolts on the rear edge that are hard to get to with the seat in. I've done it both ways.

I've got a question. What is the height difference between the two humps? Mine has a C6 from the factory and the hump looks fairly low. My parts truck is the same way.

[snake]

Yeah - are there actually two different size bolt on humps?? I always thought that is was just a matter of either the solid floor pan being continuous or you have a bolt on 'tunnel cover' that is raised higher than the floor pan. I think I've only ever seen one version of the bolt on cover.

[Racer Z]

They would not make two different cabs, that's not cost effective. It's cheaper to make one cab and a variety of bolt-on covers. One for the stick shift trans and one for the column shift trans. As pointed out, possibly a third to clear a fatty like the C6.

Which brings us back to the original question. What is the actual differences in the tranny covers.

[snake]

By 'two different cabs' are you referring to one with the opening in the tunnel area of the floor and one without the opening??

They definitely made both versions as I've had (and currently have) both. The ones I've had without any opening in the floor tunnel were '67 and '68 model year so maybe it was a year thing...??

So as I'm typing this I remember I have several of these on a shelf in the shop so I might as well go look at them to see if there are two versions with different 'depths'. Of the four I have, they are all the same regarding the depth or amount they rise up above the truck floor pan(~2" at the deepest point). However, now that I looked at them closer, it was intersting to notice that there are at least three different versions regarding how they are built (not just if they have a hole for a four speed floor shift). One I have is actually two pieces with the seam going across left to right near the mid point front to back. This one is fairly lightweight material and happens to have a rectangular hole for shifter(probably not a factory hole). Two others I have are much heavier (thicker metal) and are stamped from one piece of metal - one with a round shifter hole that appears to be factory and another of same constuction with no shifter hole. The fourth is still bolted in so I don't know the material weight but it has a fairly well defined line across the top with 'ripples' at the mounting flange (at the same location of the seam on the first one above) so it has a slight bend. The heavier ones did not have this and appear to be perfectly straight.


Anyway - I'm just rambling now and I doubt any of this info is useful to anyone. Just thought I'd pass on what I noticed.

[Racer Z]

By 'two different cabs' are you referring to one with the opening in the tunnel area of the floor and one without the opening??

Yes.

They definitely made both versions as I've had (and currently have) both. The ones I've had without any opening in the floor tunnel were '67 and '68 model year so maybe it was a year thing...??

Interesting.

I have a 69 and 70, both F250, both came with 360/C6. Both have the same 2 inch cover pan.