Two 1979 Chevrolet 305 listings can have different carburetor numbers and still share a distributor. Chevrolet’s factory service manual shows exactly that for the K-10 in its Federal manual- and automatic-transmission rows: both list distributor 1103374, but their carburetor numbers differ. Across the four groups within those two Federal 305 rows, the chart lists three distributor models. To follow it, you need more than the engine size.
The source is Chevrolet’s 1979 Light Duty Truck (Series 10–35) Chassis Service Manual, ST 330-79, printed page 6E-29. Its two 5.0-litre (305 C.I.D.) rows identify VIN U and LG9, then separate manual and automatic applications. Within each row, a dashed line divides the carburetor, distributor and vacuum-model columns into aligned upper and lower branches.
Here is a limited extraction of those branches. All four entries belong to those Federal 305 rows. Application abbreviations and W/AC qualifiers are retained as printed; an unmarked number is left unmarked rather than given an inferred equipment restriction.
Federal/manual, upper branch
- Application within the branch: CG-10
- Carburetor identification: 17059143; 17059145 W/AC
- Distributor model: 1103381
- Vacuum model: 1973691
Federal/manual, lower branch
- Application within the branch: K-10, C-20
- Carburetor identification: 17059101; 17059103 W/AC
- Distributor model: 1103374
- Vacuum model: 1973693
Federal/automatic, upper branch
- Application within the branch: C-10 G-10
- Carburetor identification: 17059142; 17059144 W/AC
- Distributor model: 1103369
- Vacuum model: 1973644
Federal/automatic, lower branch
- Application within the branch: K-10
- Carburetor identification: 17059100; 17059102 W/AC
- Distributor model: 1103374
- Vacuum model: 1973693
Two comparisons make this little reference useful. For the upper branches, moving from manual to automatic changes the distributor from 1103381 to 1103369, along with the carburetor and vacuum-model entries. For K-10 in the lower branches, the carburetor entries change between manual and automatic while distributor 1103374 and vacuum model 1973693 remain the same. The manual’s own pattern is more specific than either “all 305s use the same distributor” or “each carburetor number requires a different distributor.”
The manual row has the broader application heading CKG-10, C-20; the automatic row has CKG-10. Keep those headings with the branch labels when saving an extract. C-20 appears in the manual lower branch here, not in the automatic row. Likewise, CG-10 in the manual branch and C-10 G-10 in the automatic branch remain in their original printed forms.
These entries are a starting point for comparing a recorded component number with a particular 1979 chart application. They do not establish which component was installed on a surviving truck, supersessions, or modern replacement interchange. The chart’s timing, idle and advance specifications are outside this identification-only extract; this page is not a tuning or repair procedure.
Source: Chevrolet, 1979 Light Duty Truck (Series 10–35) Chassis Service Manual, ST 330-79, printed 6E-29, Fig. 6E-40, “Engine Performance Specifications,” final two main rows, PDF page 818. View PDF page 818.