will 1976 3/4 parts fit my 66 gmc

[poco64]

I spent yesterday researching to see if I can use this parts truck for my project. Wow what a lot of good info. Its much more info than I can process so I will ask specifically about this project. I can purchase a 1976 camper special 3/4 ton, 8 hole wheel, 14 bolt diff which I will assume for now is a 3.73 gear ratio fairly reasonable with the complete front cross member with disc brakes. I want to use this for parts on my 1966 3/4 ton gmc, 8 hole wheel fleet side that has the original front cross member, and a 10 bolt 4.11 rear end. will this be a fairly simple bolt in project? Will the master cylinder brake assembly bolt in easily? I understand that i should check to make sure it has 1.25 calipers. How do i tell if it has 1.25 calipers? Should I change the cross member out, or just the parts? The front clip is off and the motor is out. I am going to drop in a 383 stroker and an auto trans. thanks for any information.

[LostMy65]

Those years have good upgrades for your truck. You will want to roll out your whole front crossmember and then roll in the whole newer.
The newer crossmember bolts up with just one new hole and one wallowed.
.
Take a look at the FAQ's Stickied at the top of this forum and you'll find at least 3 really detailed threads on both the front swap, and the 14-bolt. Also take a look at my 66 Service Truck build thread linked in my Signature.
Welcome to the forum.

[franken]

On 67-72, which I think is similar to the earlier trucks, the spring perches on the rear are closer together than most 73+ trucks. Dual rear wheel diffs may have narrow perches. At least one shock mount is different.

If you can get the 73+ springs and frame mounts, I think you can drill the frame and bolt them on. The frames are the same width. The spring mounts provide the extra width.

[LostMy65]

Actually, franken,
He will want to keep it simple and just bolt the 14-Bolt to his Trailing Arms.
The thread Titled: "Another 14-Bolt Conversion" covers the topic well.

[LostMy65]

Here's the 14-bolt thread
http://67-72chevytrucks.com/vboard/s...d.php?t=624445

[64shortbox]

To keep things real simple DON'T cut or destroy any of the brake lines off the parts truck. I found with some careful & slight tweaking I was able to use ALL the factory hard brake lines & it looks like they were made for my 64 C10. I did have to build a bracket for the proportioning valve or combination valve as they call it but it kept me from having to make all new brake lines.
Oh, when you go to bleed the brakes after the swap is completed make it easy on yourself and get a proportioning valve centering tool they're about $8.00 on eBay if your local parts house don't stock them. They hold the valve centered when you're bleeding the brakes. You unscrew the plastic switch on the proportioning valve (the one with the light brown wire attached to it) and screw the tool onto its' place, bleed your brakes as normal, remove the tool when done and screw the switch back in. No need to worry about fluid loss, it's dry where the switch screws into the proportioning valve.

[poco64]

thanks for the help guys. Both the 76 and the 66 have leaf springs. Does the brake master cylinder bolt on to the firewall or do I have to drill holes or cut a spot? Will I have to use the brake clutch assembly from the 76. I have no experience with that .

[Captainfab]

If you want to use the '76 brake booster, yes you will have to drill holes to bolt it up to your firewall. If you don't want to do that, I make booster brackets that are a bolt on using the factory holes. But you will have to use a different booster. I would leave the original pedals and bracket.

Originally Posted by poco64

thanks for the help guys. Both the 76 and the 66 have leaf springs. Does the brake master cylinder bolt on to the firewall or do I have to drill holes or cut a spot? Will I have to use the brake clutch assembly from the 76. I have no experience with that .

[poco64]

Captianfab which booster would work with your bracket?. My neighbor has a whole bunch of donors laying aroumd his yard. From what I gather I would also need your adapters for the power steering?

[franken]

Originally Posted by LostMy65

Actually, franken,
He will want to keep it simple and just bolt the 14-Bolt to his Trailing Arms.
The thread Titled: "Another 14-Bolt Conversion" covers the topic well.

Good plan. I have leafs so trailing arms never entered my mind...

[LostMy65]

Originally Posted by franken

Good plan. I have leafs so trailing arms never entered my mind...

Funny
I had trailing arms so assumed he did too.

[Captainfab]

There are links to most of my for sale threads in my signature line. Here is the one for the power brake booster brackets.

http://www.67-72chevytrucks.com/vboa...d.php?t=339081

Some of the compatible boosters are mentioned in post #1 and there is a more compete list in post #183 on page 8. Additionally the booster bracket comes with a list.

Yes you will need a power steering box adapter plate.

Originally Posted by poco64

Captianfab which booster would work with your bracket?. My neighbor has a whole bunch of donors laying aroumd his yard. From what I gather I would also need your adapters for the power steering?

The '63 and up GMC's typically had rear leaf springs.

Originally Posted by franken

Good plan. I have leafs so trailing arms never entered my mind...

Originally Posted by LostMy65

Funny
I had trailing arms so assumed he did too.

[64shortbox]

Definitely get your Booster Bracket from Captainfab. His pieces are top notch & even come with mounting hardware. I purchased both his Booster bracket & his Power Steering Bracket and there's none better. The template he supplies for the power steering bracket is spot on and he even supplies new grade 8 bolts & easy to understand instructions with it.
I've also included a picture of the proportioning valve tool that holds the valve centered. It's made out of plastic (I think they all are) but it gets the job done.