Halfbreed - GMC Z71 + IH Extd Cab

[sparkydog]

Saturday morning off came the back of the cab.

Note - no real GMC trucks were harmed in the filming of this movie...

[sparkydog]

Next I fabbed up a quick little frame so I could support the brake MC and the fender skirts when I take the floorpan/firewall off. I know it looks stupid but it works.

The floorpan is up off the shock mounts and is ready to come out. All I'm waiting on is freon evac on Monday afternoon and I can pull the HVAC unit out.

[89muscletruck]

Cool!

[Palf70Step]

Interesting build. This I want to see!!

[sparkydog]

Once I had the HVAC unit out of the GMC carcass I proceeded to do a magic swap.

[sparkydog]

And then I finished the swap. This was just for s and g's. I wanted to study the initial fit of the IH floor and firewall before I started cutting on the GMC floor/firewall. I'm ready for bed. Not bad for 1 guy and no brains or brawn... or hoist... or crane... or help.

[67ChevyRedneck]

Give yourself a little more credit

It's looking great. I'm really diggin' it.

[67_C-30]

Oh man! Subscribed! I love builds like this!

[sparkydog]

Here's a teaser shot from last night. I slapped a front fender on so I could visualize some of the fore/aft position issues. The cab is sitting at least 3" and perhaps as much as 5" higher in these photos because it's up on blocks.

I'll probably end up putting the firewall of the cab another 3" forward and shifting the front wheel farther back in the wheel well opening of the fender. Where it is now is almost exactly where I would leave it if I never planned on shortening the front. But from the very start I wanted to change the look of the factory truck so I'm still heading in that direction. With the cab farther forward the stock fender will look stupid with the wheel so far off center of the opening, but then I will do the sectioning of the fenders and hood to shorten them up.

...sigh... but first I gotta get the GM floor pan and firewall rough cut, the IH cab floor and firewall cut out and the two pieces married up.

[67_C-30]

I can't wait to see more!

[sparkydog]

When I got the GMC firewall off the frame I noticed the signs of a coolant leak on the back of the left head on the motor. Anyone got an opinion of how serious that is? Intake man gasket or worse?

[BlueJeep]

Intake gasket. All the 5.7 vortecs do that...

[Palf70Step]

Heck dang near every semi modern Chevy Small block has had that issue, until a real gasket is put in place.

[67ChevyRedneck]

It also happens from never changing out the dexcool. It's becomes corrosive to gaskets after it's reached it's lifespan.

[sparkydog]

Thanks for the gasket opinions! I know (or at least expect) that I will have some maintenance issues with the GM chassis once I get to the point of trying to run it. I'm even prepared for the motor or tranny to be shot. At this point I want to try to stay focused on transplant tasks and leave the GM repair/maintenance for later. Sounds like I can add this item to the "to do" list and work it later.

[Sven]

Cracking project, Sparky ... I'm sticking around, this'll be legendary to watch ...

Have you seen the Trucks TV show where they're transplanting a 70s Ford body on a Ram 2500 chassis?

-Steve

[nuke1]

Looking good! I have a soft spot for the old BINDERS! I got a 79 Scout Ralley II, mom and dad bought it new. One day i will get to it.

[sparkydog]

Originally Posted by Sven

Cracking project, Sparky ... I'm sticking around, this'll be legendary to watch ...

Have you seen the Trucks TV show where they're transplanting a 70s Ford body on a Ram 2500 chassis?

-Steve

Yes I have. I had already bought my 2 trucks before I ever saw the show but wasn't doing anything with them. The show helped motivate me. Then, one day I saw Chip Foose in the Orange County airport and blurted out "Hi Chip" and he said "Hi" back. That was my "sign" to proceed with the project so I did.

[sparkydog]

OK next installment: these next posts took me a total of about 3.5 hours to accomplish. And in my 20's or 30's I could have done this stuff and then gone out and partied like a rock star. But now at 51 I had to take 2 Aleve and guzzle a couple of Margaritas just to make the pain in my wrists and fingers go away after all the sawzall and disk cutter time.

So to start with, on Wed and Thurs night I moved the IH cab unit up to the back of the GMC frame to make way for the re-install of the GMC floor pan.

On Thurs night I marked off the GMC floor pan for the cuts and today I shaved the floor and firewall.

[sparkydog]

Had a little excitement when the freshly cut floor and firewall decided to make a break for freedom.

Got the horses back in the barn, then sanded all the cut edges and then stuffed the GMC floor pan back where it belongs and put the shock mounts back under it.

[sparkydog]

Next I solved a lot of my cowl and floor rot problems on the IH cab (by cutting them off hah!). I'm extra glad I chose to go this route because after I cut open the front cowl and firewall of the IH I discovered "the sarcophagus" inside the IH cab rocker panels. Here are some before and after pics. This does not include the 4lbs of dirt and rust that shook out into my face, ears and eyes while I lay on my back cutting this stuff open.

[sparkydog]

Being that I am so old and feeble I took a break at about this point and cleaned and organized. I may be done with the cab dolly so I tucked it away and then set up a little boneyard near the front sidewalk so everyone can stare at my wreckage.

Then I manned up and slid the cab forward and got it as close as I could so I could start making plans for the next round of trimming.

[sparkydog]

Here's two more shots of what I will be dreaming about while I sleep...

Also up with the next cuts will be taking out the old floor of the IH cab and mocking up both the fore/aft location and how much if any body drop to do over the GMC floorpan.

[67ChevyRedneck]

Very cool!

Some friendly advice? In case you weren't planning on doing this, I'd set the cab in place (out of the way) and fully mount the bed the way you want it (wheel well centered, bed height, etc...). That way, you don't accidentally mount the cab "too low" and have to raise the bed floor, that is, if you didn't want to do that. Just offering up an idea. It's looking great

[sparkydog]

Originally Posted by 67ChevyRedneck

Very cool!

Some friendly advice? In case you weren't planning on doing this, I'd set the cab in place (out of the way) and fully mount the bed the way you want it (wheel well centered, bed height, etc...). That way, you don't accidentally mount the cab "too low" and have to raise the bed floor, that is, if you didn't want to do that. Just offering up an idea. It's looking great

Yes you are spot on about the bed. Part of the mockup of the cab and the decision of how much body drop to put in will be the ride height of the bed. I am going to shave a few brackets and things under the bed but will NOT be trying to alter the floor height in the bed. So whatever is the lowest the bed will go onto the GMC frame is where the ride height of the cab will go.

However I am not going to mount up the bed just yet. That is because I already know I have to section it about 15-20 inches (lengthwise) and I'm just tired of cutting right now. So I am going to revert to "SuperEngineer" and just measure all the stackups on the bed and transfer over to the cab. Then I may go a little bit lower on the cab - I can always shim it back higher if the bed comes out different than what I measure.

Thanks for watching my back on the build Redneck!