GMC 1500 Leaf Springs

[Pharmhand3]

Hello All,

Thought I would throw a question out to the board to see if anyone has any input for me. I have '70 GMC 1500 Fleetside that I bought in 1999 for $350. The history between then and now is too long, and has been recently discussed on the Engine and Drivetrain board (Need Help!! No Oil Pressure!!), so no details here.

Anyway, when I bought the thing the guy told me it was a 'heavy half' instead of a regular half-ton truck. The rear end has leaf springs instead of coils. I was curious to know if the truck came from the factory with leaf springs as an option? Or was it standard on the GMC trucks? Or perhaps a dealer mod?

What's really interesting is that the leaf springs are two-teir, as if they have a set of leaf springs stacked on top of another set, then all bolted together.

Anybody got a clue on this? The truck does have what appears to be the mounts for the left and right control arms (for a coil spring setup). But I figured that was probably a standard mount for the frame during the assembly phase.

Thanks for you help!!

[Longhorn Man]

do you have a photo of the springs by chance?
Is there anything listed in the glove box?


There is no such thing as a heavy half in 67 - 72. That option came into play in the 73 - 87 model run, and it was a numbers game to get around emissions requirements. Normally ppl who don't know what's up will call the older trucks (70 and older) heavy halfs becouse they have 6 lug wheels... but again, they are misinformed.
Normally, GMC trucks recieved leafs standard, with coils optional, which is backwards from the chevy side of the house. There were exceptions to the rules, and without looking through mynotes.. I think 69 GMC trucks had coilos standard... but as a rule of thumb, expect leafs under a GMC.

[Pharmhand3]

Great!! Thanks for the good information. I'll see if I can get a picture posted over the weekend.

[Ozona]

My '72 is leaf spring, standard option. Sounds like somone bolted on a set of helper springs to tow or haul heavy.

[49studebaker]

Yes, I agree with the other guys. My 71 GMC has heavy duty coils in front and heavy duty leafs in back but they don't look like the ones you're discribing. Sounds like an add-on for sure.

[Longhorn Man]

Ozona... were yours standard, or option?

[Ozona]

Originally Posted by Longhorn Man

Ozona... were yours standard, or option?

They are listed on the protectoplate. I don't know if that means they're special. They're just plain ol' leaf springs under there.

[Longhorn Man]

That would be optional then.
It would be listed on the SPID label... or option label, but not on the protecto plate. The protecto plate was kinda like a credit card with embossed numbers used for ID durring warranty claims.

[badpeanut]

I saw this '72 GMC 4x2 in the junkyard with "G50 Heavy Rear Spring" in addition to G70. The other leaf spring trucks I've seen only have G70. The leaf packs were still there, but some were broken and somebody must have added more because the packs were massive.

[Ozona]

Originally Posted by Longhorn Man

That would be optional then.
It would be listed on the SPID label... or option label, but not on the protecto plate. The protecto plate was kinda like a credit card with embossed numbers used for ID durring warranty claims.

OOps. sorry. tired.

Correct.

It's listed on the sticker on the inside of the glovebox.

[MadDog]

It sounds like you just described my setup, I have the leaf springs on my 70 GMC, and the additional springs i put on myself, they are the overload springs. They simply help when your hauling heavy loads.

[Pharmhand3]

I finally got around to taking some pictures of the leaf spring set-up.

[jerry moss]

factory installed overload springs were available on both leaf and coil trucks, i have a set off a 68 GMC in my storage unit but i couldn't get the frame brackets as the truck was sitting on the ground and the springs were already removed when i found it.

[49studebaker]

The springs in the picture looks like they were overload springs meant to go "under" the factory springs. Only problem is the axle would have to be on top of the leafs, not under them.

[Longhorn Man]

No, those are right... here's mine, 70 one ton longhorn w/oveloads, all stock.. at least, in this area anyways.
The weight of the truck makes the axle go up (in relationship to the body) and once the springs hit that L bracket, you are riding on them.