Two trucks could share the C-2500 name and have different suspension specifications in GMC’s 1986 pickup brochure. The technical table gives C-2500 two neighboring columns, with different springs, shocks and front stabilizer entries. Even before getting into the options, there are differences in what GMC listed as standard.
The table separates them by Standard GVW: 6,400 lb in one column and 8,600 lb in the next. The latter carries a short footnote, “Requires C6P on 2-door cab models.” For a two-door cab, C6P is therefore part of the 8,600-lb entry. These are the two-wheel-drive C-2500 entries in GMC’s 1986 United States brochure, rather than a general specification for every truck wearing the name.[1]
Start with the springs
Some entries match. Both C-2500 columns sit under the description “independent, coil springs” for the front suspension, and both list a front-suspension capacity of 3,800 lb. The spring figures on the next line differ, though.
The standard front spring capacity is 1,750 lb in the 6,400-lb column and 1,900 lb in the 8,600-lb column. At the rear, the standard spring entries are farther apart: 2,000 and 3,000 lb respectively. GMC’s footnote defines these spring figures as “At ground, each.” Those are individual spring capacities, not the amount of cargo the truck could carry.[1]
There is some overlap in the options. The 6,400-lb column offers a 1,900-lb front spring capacity and lists 2,600 and 3,000 lb for optional rear springs, using the same per-spring definition. A spring figure can therefore appear as optional in one column and standard in the other. The same spring figure appears in both columns, but in different places on the equipment list.[1]
The shocks follow the same pattern
GMC lists 25-mm standard shock-absorber diameters at both ends in the 6,400-lb column. The 8,600-lb column lists 32 mm front and rear. Look at the Optional rows, and the lighter column also offers 32-mm shocks at both ends.[1]
A reference to 32-mm shocks would fit entries in both columns, although their standard equipment differs. A truck’s own records would still be needed to establish how it was ordered, and this brochure cannot tell us what parts a surviving example carries now.
The front stabilizer has its own entries
In the 8,600-lb column, GMC lists a 1.06-inch front stabilizer bar as standard and 1.25 inches as optional. The 6,400-lb column puts a dash in the Standard row and prints “1.06/1.25” under Optional. Here, too, a size listed as standard in the 8,600-lb column also appears among the choices in the 6,400-lb column.[1]
The two columns share a front-suspension description and capacity, yet their standard spring and shock entries differ. Several of the 8,600-lb column’s standard figures also appear in the 6,400-lb column’s optional rows. That overlap is part of what makes this page interesting: one of those shared figures would not settle which complete set of specifications you were reading.
C-2500 is a familiar name, but GMC’s own brochure leaves more of the equipment story to the Standard GVW heading and the choices underneath it. For these 1986 two-wheel-drive trucks, the springs, shocks and stabilizer entries give the two versions their separate identities on the page.
Source
[1] GMC, 1986 GMC C/K Pickups, edition 7369-86USA, actual PDF page 11, “TECHNICAL INFORMATION,” 2-WHEEL DRIVE panel, the two C-2500 columns; FRONT SUSPENSION and REAR SUSPENSION groups, and footnotes 1 and 5. No printed page number is visible. Original manufacturer brochure scan hosted by XR793: View the original 1986 brochure, PDF page 11