Are C-30 & C-20 Rear Leafs Interchangeable? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

69sixpackbee · 03-30-2005, 02:47 PM

Will the 11,000#, 7-leaf springs from a C-30 bolt up to the hangers and shackles of a '72 C-20?

Rod · 03-31-2005, 10:34 AM

Hollander Interchange manual mentions both being the same size 2 1/2 inch by 26x26. Those two sizes being the 3/4 C20 version to the 11000 axle 1 ton version.

Make sure its a 11000 lbs 1 ton version as the 7500 lbs 1 ton version are 19 3/4 by 19 3/4 which is shorter.

The way it looks in the book is that 3/4 tons had either 5 or 6 leafs while 1 ton had 7.

On my own 1 ton I have a 8 in the main pack and 7 in the auxillary..15 total.

**JIMs70GMC** · 03-31-2005, 05:07 PM

I have some 71 C20 leaf springs in my garage that are not that wide, closer to 2" wide. I'll measure them to make sure.

Where's post #2?

**CPNE** · 03-31-2005, 05:11 PM

Quote:

Originally Posted by JIMs70GMC

Where's post #2?

PM for details

69sixpackbee · 03-31-2005, 06:55 PM

Mine are the 2" wide, 7-leaf versions. I do not have overloads but I do have the Ride-rite bags on the truck. I notice it is a little "wavy" at times with my camper on it. I do have brand new Rancho 9000's, sway bars and good heavy tires. I only need about 40 PSI in the bags to get the truck level with a full load. It is possible that I have a mismatched set of tires on it (BFG's in the front and Cooper's in the rear). I was just wondering if I would benefit by putting the C-30 springs on it. I would'nt have room for an overload pack and the bags because I would not be able to fit the bags atop the springs and into the bracket.

BobS · 03-31-2005, 09:39 PM

My 71 C30 springs are 2 1/2 inches wide by about 51 inches eye to eye. 6 leafs in the main pack and 1 auxilliary leaf. It's a Longhorn.

Bob

Rod · 03-31-2005, 10:01 PM

six pack bee...your rear diff a eaton or dana? Not sure it makes a difference but thought I'd ask.

**JIMs70GMC** · 03-31-2005, 10:03 PM

I'll add the leafs I have were with a dana 60.

69sixpackbee · 04-01-2005, 12:33 AM

I have the Dana 60 rear.

03-30-2005, 02:47 PM	#1
69sixpackbee Registered User Join Date: Jan 2001 Location: Sabinal, Texas Posts: 1,706	Are C-30 & C-20 Rear Leafs Interchangeable? Will the 11,000#, 7-leaf springs from a C-30 bolt up to the hangers and shackles of a '72 C-20?

03-31-2005, 05:07 PM	#3
JIMs70GMC user # 2756 Join Date: Jun 2001 Location: Chesapeake, Virginia Posts: 4,612	I have some 71 C20 leaf springs in my garage that are not that wide, closer to 2" wide. I'll measure them to make sure. Where's post #2? __________________ 1970 K25, 8' stepside bed 350/465/205 44 up front, 60 in the rear 4.10s rolling on 33" Dunlop MTs 1986 K5, 350/465/208 Dana 60/14 bolt from a cucv 36" Super Swampers TSL/SX 1983 K20 w/ CUCV axles, 350/700R4/208 sitting on 37" Goodyears 1986 M1031 6.2 diesel, TH400/NP205 locker in the rear and a LS in the front, all stock for now..... 1986 K30, 350/400/205 dana 60 and 14 bolt. I kept the drivetrain. Body/bad and chassis are gone. 1981 K30, 350/465/205 dana 60 and dually 14 bolt. Has a G80, and a flat bed. Going to replace the flat bed. 1985 K20, 350/400/208 10 bolt and SF 14 bolt. I wonder where I can find some 1 tons. Hmmmmm

03-31-2005, 09:39 PM	#6
BobS Senior Member Join Date: May 2001 Location: West Central Minnesota Posts: 568	My 71 C30 springs are 2 1/2 inches wide by about 51 inches eye to eye. 6 leafs in the main pack and 1 auxilliary leaf. It's a Longhorn. Bob __________________ V-6....only GMC Trucks have it! 62 GMC W5000 NAPCO-V6 65 GMC 2500 NAPCO Panel-V6 66 GMC 1000-V6 66 GMC 1500-V6 67 GMC K1500-SBC (originally a KM-V6) 68 GMC C1500-V6 68 GMC C1500-V6 68 GMC Suburban C2500 70 Chevy K20-SBC 71 Chevy C30 Longhorn-SBC 72 GMC Suburban C1500-BBC 72 Chevy C10-SBC 72 GMC C5500-ToroFlow Diesel

03-31-2005, 10:01 PM	#7
Rod Join Date: Dec 1999 Location: Eastern - Manitoba Canada, Winnipeg Posts: 4,369	six pack bee...your rear diff a eaton or dana? Not sure it makes a difference but thought I'd ask. __________________ Senior active founding member. 70 3/4 ton GMC Suburban 4x4 250/4 spd. 71 1/2 ton Suburban Chevy 4x4, 350/350 72 Chev 1 ton tow truck 402BB w/Holmes 440 wrecker on propane 2005 FLSTSCI Harley Springer 85 FXSB Harley Lowrider 72 Triumph 650 Bonneville 5spd "Poor people don't have hobbies" Quote from wife.

03-31-2005, 10:03 PM	#8
JIMs70GMC user # 2756 Join Date: Jun 2001 Location: Chesapeake, Virginia Posts: 4,612	I'll add the leafs I have were with a dana 60. __________________ 1970 K25, 8' stepside bed 350/465/205 44 up front, 60 in the rear 4.10s rolling on 33" Dunlop MTs 1986 K5, 350/465/208 Dana 60/14 bolt from a cucv 36" Super Swampers TSL/SX 1983 K20 w/ CUCV axles, 350/700R4/208 sitting on 37" Goodyears 1986 M1031 6.2 diesel, TH400/NP205 locker in the rear and a LS in the front, all stock for now..... 1986 K30, 350/400/205 dana 60 and 14 bolt. I kept the drivetrain. Body/bad and chassis are gone. 1981 K30, 350/465/205 dana 60 and dually 14 bolt. Has a G80, and a flat bed. Going to replace the flat bed. 1985 K20, 350/400/208 10 bolt and SF 14 bolt. I wonder where I can find some 1 tons. Hmmmmm

03-31-2005, 10:34 AM	#2
Rod Join Date: Dec 1999 Location: Eastern - Manitoba Canada, Winnipeg Posts: 4,369	Hollander Interchange manual mentions both being the same size 2 1/2 inch by 26x26. Those two sizes being the 3/4 C20 version to the 11000 axle 1 ton version. Make sure its a 11000 lbs 1 ton version as the 7500 lbs 1 ton version are 19 3/4 by 19 3/4 which is shorter. The way it looks in the book is that 3/4 tons had either 5 or 6 leafs while 1 ton had 7. On my own 1 ton I have a 8 in the main pack and 7 in the auxillary..15 total. __________________ Senior active founding member. 70 3/4 ton GMC Suburban 4x4 250/4 spd. 71 1/2 ton Suburban Chevy 4x4, 350/350 72 Chev 1 ton tow truck 402BB w/Holmes 440 wrecker on propane 2005 FLSTSCI Harley Springer 85 FXSB Harley Lowrider 72 Triumph 650 Bonneville 5spd "Poor people don't have hobbies" Quote from wife.

03-31-2005, 06:55 PM	#5
69sixpackbee Registered User Join Date: Jan 2001 Location: Sabinal, Texas Posts: 1,706	Mine are the 2" wide, 7-leaf versions. I do not have overloads but I do have the Ride-rite bags on the truck. I notice it is a little "wavy" at times with my camper on it. I do have brand new Rancho 9000's, sway bars and good heavy tires. I only need about 40 PSI in the bags to get the truck level with a full load. It is possible that I have a mismatched set of tires on it (BFG's in the front and Cooper's in the rear). I was just wondering if I would benefit by putting the C-30 springs on it. I would'nt have room for an overload pack and the bags because I would not be able to fit the bags atop the springs and into the bracket.

04-01-2005, 12:33 AM	#9
69sixpackbee Registered User Join Date: Jan 2001 Location: Sabinal, Texas Posts: 1,706	I have the Dana 60 rear.



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