Big10/Heavy Half

[79 Big10]

it is my understanding that the Big 10s are the same as the Heavy Halfs, am I correct? I have seen quite a few Big 10s around but not very many that say Heavy Half. Also, what was the GVW rating on these trucks?

[KIILew]

And now another long winded answer, spanning a few posts…

You are correct about the Big 10’s being the same as Heavy Halfs.  In fact, the Heavy Half was the GMC equivalent to the Chevrolet Big 10.  Both were identified by the option code “F44” and contained equipment allowing higher GVW’s than those of the regular Chevy C10/GMC C15.

The 1979 model year F44 package included a choice of 1,625 or 1,700 lb front springs (1,475 and 1,550 lb front springs were commonly used on standard C10/C15’s), 2,000 lb capacity rear springs (1,550 lb rear springs were standard on regular C10/C15’s), heavy duty power brakes (manual and light duty power brakes with smaller rear drums were offered only on standard C10/C15’s), larger tires in a choice of 1,790 and 1,905 lb capacities (several smaller capacities were also listed for regular C10/C15’s) and the 305 V8 (the 250 six was standard on regular C10/C15’s).  With the exception of the 1,700 lb front springs, all of the F44 components shown above could be ordered separately on the regular C10/C15.  Depending upon the equipment selected, the regular C10/C15 offered GVWR’s of 4,900, 5,300, 5,400, and 5,600 lbs.  However, by selecting the F44 package, the buyer received all of the above equipment, plus the bodyside decal designating the C10/C15 as a Big 10/Heavy Half, offering GVWR’s of either 6,050 or 6,200 lbs (depending upon the tire and front spring capacities selected).  (You can determine your Big 10’s rating by checking the label affixed to the driver’s door frame.)

A few other notables should be mentioned.  For 1979, the U.S. EPA established fuel economy standards for trucks up to 6,000 lb GVW.  To meet these standards, GM equipped the standard C10/C15 with a special hood seal and underbody air dam, and also offered a selection of rear axle ratios biased in favor of economy.  The Big 10/Heavy Half GVWR’s exceeded the EPA’s 6,000 lb threshold, and accordingly, those models were not equipped with the hood seal and air dam.  Also, the F44 package allowed the purchase of lower axle ratios, and the 454 V8 engine option.  In contrast, the 350 was the largest engine available on the regular C10/C15.  

Prior to 1979, the EPA considered all trucks under 6,000 lbs GVW to be light duty emission class vehicles.  With few exceptions, these vehicles required undesirable catalytic converters and the use of unleaded gasoline.  The F44 option was introduced to allow buyers the possibility of buying a heavier duty ½ ton truck that could use cheaper leaded gasoline.  However, for the 1979 model year, the EPA expanded the light duty classification to include all trucks up to 8,500 lbs GVW.  Thus, the Big 10/Heavy Half (and all ¾ ton Chevy C20/GMC C25 trucks, as well) lost this particular advantage.  Only 1 ton C30/C35 series remained exempt from catalytic converters and unleaded gas.

Excepting the differences discussed above, the Big 10/Heavy Half was identical to the standard C10/C15.  A 3.14 section modulus frame, 3,750 lb rear axle, and 15 inch wheels were common to both.  These components were much more robust in the ¾ (20 series) and 1 ton (30 series) models.

Anyway, hope some of this information is helpful!

[roger27]

someone at my church has a gmc sierra 15 in all original paint, yello,, and the back has the original yellow decal but it says big 10. my understanding was that heavy half was what it was called untill a certain year, then they changed the name to big 10. but idunno.

[glvander]

Were there many Big10s with shortboxes?

My father ordered 1, but Chevy wasn't going to release it until the dealer told them that it wasn't going to be used on the road.  

[R2R]

Did Chevy produce Big 10 other years than 1979?????
 They did,,,,, didn`t they. If so could you tell me if the 1979 specs you were talking about would be the same for a 1974????

[MrBlonde]

I have seen a couple of Big 10 shortboxes. One was a nice black one parked on the street, and the other was a brown one in the movie Happy Texas.

[ChevyGuy]

my truck is a 76 long bed and its a heavy half.

[smokin77]

my trucks an 85, with quad shocks and it looks lifted compared to regular k10s, is that a "big 10"?

[oscarone]

my'77 k10 is a shortbox with a gvwr of 6200.

[Fast68]

quad shocks came on the trucks startign in 82, no its not an F44,

look on your SPID label on your glovebox door in the options list for F44 code

i have had a 78 Big 10 mysel,f and have seen several around


go here and click on 73-87 info: www.73-87chevytrucks.com/

read it all, you will learn new info,,

[Froggy]

I have a 78 big 10 short box that needs restoring. It came with a 250 straight six, 3 speed tranny and a possi rear. Great truck.

[Klondike]

We use those to plow snow