C20 compared to c10

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jsigl

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Hello all I’m new to square family got a 1980 C20 looking through the posts people are saying c10 and c20 frames are the same and then in the next thing I search is the cab the same. I get yes the frame mount to cab is taller because the frame is different. I just read the frame is the same but now it sits lower and needs a taller mount. Can someone please explain what is correct here. Thanks a bunch
 

BSquared

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My understanding is that the C20 and C10 frames are the same. Anyone please chime in and correct me if I am wrong, as I would like to know as well. I have never had a C20 but having both a K10 and a K20, the frames and body mounts appear to be the same between them. I would imaging the C10 and C20 would be the same.

A frame related difference between C and K (2wd and 4wd) is just that the leaf spring hangers are longer, or hang down more on the 4wd. The frame itself appears to be the same.

The only body mount differences I'm aware of is the 73-80 years differ from the 81-87 years. If you are swapping bodies, you buy the body mounts for the frame year, not the body year.

The C30/K30 have their own taller frame, as do crew cabs.
 

BSquared

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Not relevant to OP's questions, but I did leave out that 2wd and 4wd frames have different crossmembers under the engine. The 2wd has the big "girder beam" that all the front suspension bolts to. The 4wd has a small zig zag shaped crossmember.
 

Strick

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My 79 C20 Crew definitely has a taller frame than my 79 Big Ten C10. I have a piece of a D30 CUCV and the frame is tall like the C20 Crew, but it was mentioned earlier that the Crew trucks have a tall frame. The single cab structure is the same as far as I know. There are different floor centers depending on year, transmission and drivetrain layout.

Strickland
 

Craig 85

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It's been mentioned here before, but if I recall the C10/C20 frames are similar, but infact the metal is slightly thinker on the 3/4 ton. I thought the cab mount were the same between the C/K. I've never changed them though.

@BSquared the C/K frames are totally different from the firewall forward.

@Strick the C20 3+3 frames are actually 1- ton spec frames.
 

TotalyHucked

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Yeah frame differences are muddy water. I believe what Craig^ said is correct, 20 frames are slightly thicker though dimensionally they're the same. I can confirm that 4x4s used a different crossmember and rear cab mounts from a 2wd.
 

Strick

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Oh yeah, the frame's a taller profile like the ton stuff I play with.

Strickland
 

WFO

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Yeah frame differences are muddy water. I believe what Craig^ said is correct, 20 frames are slightly thicker though dimensionally they're the same. I can confirm that 4x4s used a different crossmember and rear cab mounts from a 2wd.
I understood that only the C6P optioned 3/4 tons had thicker frames.
 

bucket

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I understood that only the C6P optioned 3/4 tons had thicker frames.

I believe that wasn't the case for every model year, including Suburbans. Huck mentioned "muddy water" and that is 100% correct.
 

82BBC20

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My 82 C20 has the C6P option which says heavy duty chassis.
 

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oldretiredafguy

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Maybe these will help:

1973-1980
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1981-1987
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ali_c20

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