BBC Transmission Tunnel - High or Low!?!

[LOW 7FO]

Hello All. 1975 factory big block truck here. Also has TH400 although I cannot prove it is the original trans. From everything I read it says that I should have the high trans tunnel...but I don't! I have the low tunnel and the carpet kit I bought for the 1975-1980 with TH400 does not fit the tunnel area worth a darn (way too loose).

So...is it possible that this truck came with a TH350 and received the low hump? Other thoughts? I know the VIN is accurate and the truck is a factory big block so I am kind of lost now as to what the heck is going on.

I am now going to just order the 80/20 loop carpet for the 73-74 trucks since I like that better than cut pile and now I know it will fit my trans tunnel...

[c10454]

I have a stock 1976 c10 with original 454 and TH400 and I have the low hump. My understanding is the 4x4 or K series had the high hump.

[LOW 7FO]

Originally Posted by c10454

I have a stock 1976 c10 with original 454 and TH400 and I have the low hump. My understanding is the 4x4 or K series had the high hump.

Have you ordered a carpet kit for your 2WD? If so you might be lead to believe you should order the 75-80 2WD w/Th400...but that would not fit your floor since you also have the low hump. I learned the hard way, but should have known by the look of the tunnel that it was low before ordering.

[Titomars]

I have a 77 C/10 with a factory 454 and TH400. It has the low hump.

[bigblock73]

1975 bigblock auto truck here...low hump. As stated above, 4by and I believe manual trans trucks were high hump.

[Keith Seymore]

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

4wd or any floor shifted manual trans = high hump

K

[LOW 7FO]

Originally Posted by Keith Seymore

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

4wd or any floor shifted manual trans = high hump

K

This is why I am confused....look at the link to the carpet! It says 2WD and 4WD use same trans tunnel with TH-400. We know that is not the case now with the above information from several members.

http://www.classicindustries.com/pro...tk16201c2.html
1975-80 Chevy/GMC Standard Cab Pickup with:
2 or 4 Wheel Drive
TH400 Transmission
(THIS CARPET WOULD BE LOOSE ON THE LOW TUNNEL)

http://www.classicindustries.com/pro...tk16201c1.html
1975-80 Chevy/GMC Standard Cab Pickup with:
2 Wheel Drive
Column Shift (except TH400)
(THIS CARPET WOULD ACTUALLY FIT THE LOW HUMP)

So do you think the 1973-1974 carpet would be for low hump? I want this because of the 80/20 loop instead of the cut pile.
http://www.classicindustries.com/pro...tk16101b1.html

HELP ME!

[Titomars]

Keith worked the assembly line when these were built. I worked at the dealer level (GMC then Chevy). trust us C series got the low hump with column shifted 3 spds and all automatics. High humps were used with K series and any floor shifted manual C or K.
The vendor is wrong.
Ohh by the way, GM in the 70's did not put TH350s behind 454s only the TH400. If I remember correctly to order the 454 you had to order the HD trans which is the TH400.

[LOW 7FO]

Originally Posted by Titomars

Keith worked the assembly line when these were built. I worked at the dealer level (GMC then Chevy). trust us C series got the low hump with column shifted 3 spds and all automatics. High humps were used with K series and any floor shifted manual C or K.
The vendor is wrong.
Ohh by the way, GM in the 70's did not put TH350s behind 454s only the TH400. If I remember correctly to order the 454 you had to order the HD trans which is the TH400.

Excellent information I appreciate it! When the time comes to replace my current saggy looking carpet I want to get the '73-'74 loop style carpet which (according to the information above) is for a small hump truck (2WD Auto). From your experience, are the '73-'74 floors going to match the '75-'80 low hump floor? Am I over complicating this? I was so confused when I got my current carpet that I don't know what to believe anymore from the aftermarket!

[Titomars]

Originally Posted by LOW 7FO

Excellent information I appreciate it! When the time comes to replace my current saggy looking carpet I want to get the '73-'74 loop style carpet which (according to the information above) is for a small hump truck (2WD Auto). From your experience, are the '73-'74 floors going to match the '75-'80 low hump floor? Am I over complicating this? I was so confused when I got my current carpet that I don't know what to believe anymore from the aftermarket!

The 73 to 80 floor pans are the same between years. Obviously taking the hump in consideration.
When it comes time to do my carpet I want the older loop carpet too. It looks much better than the cut pile to me