Not sure, the glove box tag was gone
There are several option, I copied this from somewhere when I was trying to figure out which trucks had four, five, or six rear leaves.
The base 4,900 lb. rated C10 used the following components at minimum:
1,550 lb. capacity front springs.
1,550 lb. capacity rear springs (consisting of 4 leaves, and having a length of 52 and a width of 2.5â€).
• Front and rear tires with a load capacity of 1,470 lbs.
• Manual brake system (the 4,900 lb. rated C10 was the only pickup in the entire C/K10/20/30 lineup to use manual brakes. The front disk brakes had a diameter of 11.86†and a thickness of 1.28â€. Rear brake drums measured 11â€x2â€).
• Standard LD4 250 1 bbl. I6 engine w/M15 Saginaw 3 speed manual transmission.
The 5,300 lb. GVWR required the following minimum additions and/or substitutions:
• Option code J50 light duty power brake system (front disk and rear drum specifications remained the same as shown above).
• Option code M20 Chevrolet CH465 4 speed manual transmission (recommended at 5,300 to 6,050 lb. GVW levels when LD4 250 1 bbl. I6 engine was selected; M15 3 speed manual transmissions remained available w/larger engines).
The 5,400 lb. GVWR required all items necessary for the 5,300 lb. rating plus the following minimum additions and/or substitutions:
• Front and rear tires with a load capacity of 1,610 lbs.
The 5,600 lb. GVWR required all items necessary for the 5,400 lb. rating plus the following minimum additions and/or substitutions:
• Option code G50 heavy duty rear springs (2,000 lb. capacity for this application. These springs consisted of 8 leaves, and were 56†long x 2.5†wide).
• Front and rear tires with a load capacity of 1,790 lbs.
The 6,000 lb. GVWR required all items necessary for the 5,600 lb. rating plus the following minimum additions and/or substitutions:
• Option code F60 heavy duty front springs (1,625 lb. capacity for this application).
• Option code J55 heavy duty power brakes (this system replaced the lighter capacity J50’s single diaphragm brake booster with a dual diaphragm unit and included larger 11.15â€x2.75†rear drum brakes for C10 applications).
The 6,050 lb. GVWR package, which represents the lower of two F44 Big 10 capacities, was specifically identical, in terms of chassis and suspension components, to the 6,000 GVWR package which it superseded mid-year. Gross axle weight ratings at this GVWR were 3,100 lbs in front and 3,580 lbs. in the rear, and are the same as those cataloged for the 6,000 lb. model. The 50 lb. increase in GVWR appears to be a result of “on paper only†engineering. Emission control equipment was the only significant difference between the 1975 6,000 lb. and 6,050 lb. packages.
The 6,200 lb. GVWR was the maximum F44 option, and required all items necessary for the 6,050 lb. rating plus the following minimum additions and/or substitutions:
• Front and rear tires with a load capacity of 1,900 lbs.
• Option code LS9 350 4 bbl V8 engine w/M15 Muncie 3 speed manual transmission
