GMC Experts?????

[DANTIP]

Here is a '72 GMC with some nice options. I thought GMC's were all leaf spring rear suspension. Any ideas other than a GMC cab/bed put onto a Chevy frame?

[71swb4x4]

Coil springs were optional, I assume that's what your G50 code is.

I believe Chevrolet was the opposite, coils were standard and leafs were optional.

[DANTIP]

Would that mean that all HD rear springs for 1/2 ton 2wd trucks were coil springs?

[JCD]

I have a G50 Heavy Rear Spring, on my C-20 truck, and it's leaf springs.

J.

[Longhorn Man]

not all GMCs cme with leafs as base equipment. That's a myth. I have a chart somewhere that shows what came with what... but I haven't been able to locate it. 1/2 my info is missing/burried in boxes

[Keith Seymore]

Agree: Our 69 GMC 1/2 ton swb (bought new) was coil spring rear.

K

[sameyrasmea72]

Coils were still standard on GMC, if not the leaf option would not be listed on the spid (like below). For some reason most but not all GMC's (in 1972 anyway) had the optional leaf springs.

All the GMC's that I have owned and had leafs also had leafs listed on the spid, which tells me that it was still on option and not standard. Maybe I am wrong......

[Longhorn Man]

there were many models in the years that had leafs standard.

[GruntMoanCough]

Isn't that a Chevy spid you've got posted, DANTIP? It says Cheyenne Super equipped.

[sameyrasmea72]

T in the vin shows it was a GMC and alot of gmc's listed cheyenne super instead of sierra grande

[rollinhard]

Around here ive only seen probably 2-3 leaf rear gmc half tons out of like 50 and ive never seen a coil rear 3/4ton in person yet. Thats just here though

[DANTIP]

Thanks for the feedback! The listing of leaf springs on the SPID makes sense. I wonder why most light duty GMC's were leaf spring while most Chevy's were coil spring? It appears that at least all '72 1/2 ton trucks would have coil springs unless noted on the SPID. Therefore the SPID shown at the top looks to be correct for a GMC with coil springs.

Thanks!

[292farmer]

ive got a 72 gmc c20 with coils. heres a spid pic(no mention of coils) and a susp pic cant help it gotta show my rear off

[Youngbuck7072]

[IMG][/IMG]

[Bob B.]

Originally Posted by 292farmer

ive got a 72 gmc c20 with coils. heres a spid pic(no mention of coils) and a susp pic cant help it gotta show my rear off

You have also got a Dana 60 axle, that is pretty rare with coil springs.

[Longhorn Man]

Originally Posted by Bob B.

You have also got a Dana 60 axle, that is pretty rare with coil springs.

most of the big block 3/4 ton chevy trucks had that... not all that rare.

[292farmer]

its not a big block its a 292 I6. maybe u knew/saw that.dont know if that changes the oddity of it. i really love the ride, the gearing sucks though.... ive had to argue with so many people when getting prices on rear brakes they tell me no dana ever came with coils...especially a gmc 3/4ton grrr

[Longhorn Man]

just tell them what they want to hear. If the parts are the same as a chevy big block, then just tell them that.
I don't bother telling the parts guy that I have a cad motor in a c/30, I just get parts for a caddy.

[292farmer]

lol i know what u mean took me 30mins just to get a GM one wire alt. that was listed on the window as a sale special!!!

[Longhorn Man]

never seen a GM one wire before.

[Bob B.]

Originally Posted by Longhorn Man

most of the big block 3/4 ton chevy trucks had that... not all that rare.

I don't doubt you, but It seems most all the big block 20/2500's I have seen over the years had Dana 60's with leaf springs. I have seen a few with corporate axles and coils though.

[292farmer]

sorry its how me and my dad call an internally regulated one from a externally regulated one, summit and jegs has them too actually or at least use the term i do...sorry for that confusion!!
http://www.summitracing.com/search/?...ternator&dds=1

[BHyatt]

Try convincing someone that your Chevy came with leaf springs in the rear. They will act like they still do not believe you even after seeing the SPID.

[mr48chev]

Originally Posted by 292farmer

its not a big block its a 292 I6. maybe u knew/saw that.dont know if that changes the oddity of it. i really love the ride, the gearing sucks though.... ive had to argue with so many people when getting prices on rear brakes they tell me no dana ever came with coils...especially a gmc 3/4ton grrr

I drove 50 miles out of my way on the way home from a boat trip a couple of years ago to pick up a 3/4 ton Dana 60 only discover that it was a coil spring rear end. My GMC has leaf springs.

I would imagine when these trucks were new a lot of the GMC dealers checked off the leaf spring option with the idea of pitching leaf springs as being more heavy duty than the coils that were on most Chevrolet trucks at the time. I can remember when the trucks were new having customers with GMC trucks telling me that they were built heavier and had stronger frames than Chev trucks although both trucks were built on the same assembly lines at the time. I just let it slide by but they really believed it at the time.

[special-K]

Originally Posted by Bob B.

I don't doubt you, but It seems most all the big block 20/2500's I have seen over the years had Dana 60's with leaf springs. I have seen a few with corporate axles and coils though.

That's been my experience as well.I've rarely seen any coil Danas.A 3/4T would have been bought due to the need for a heavier duty truck,so if it was optioned out,leaf springs would have been on the priority list.Leaf springs "are" heavier duty and can be customized to a specific heavier need easier.The big block would have been ordered more for to aid the HD-ness as well.The 3.54:1 Dana 60 was paired to the automatic trans and 4spds were still considered a better bet for heavier use as well.Heck,back then many guys felt a real truck shouldn't have power steering.That was for cars .These truck really transitioned us into the comfort truck era.