If you know what terminal family you have it helps.
The detective work is made easier by having the GM factory wiring diagrams. The connector shell part numbers are in the factory wiring diagrams. Google those part numbers and you'll usually be able to identify what family they are.
Pak Con, Packard 56, and Weatherpak are the most common connectors used on the squarebodies.
This is just a list of the more common terminal families GM used on these trucks. There are others.
- 79 & later ATO/ATC Fuse panels are mostly female Pak Con terminals with Packard 56 on the flasher relays. I'm not sure on the 73-78 AGC fuse panels.
- Steering column, earlier wiper motors, and shaft mount radio plugs are Pak Con I.
- Bulkhead plugs are Packard 56 & Packard 59 terminals.
- Sensors are usually Packard 56, Sealed Metripack 150 (both standard insertion and pull to seat), and Weatherpack.
- The 12 position ALDL jacks use Unsealed Metripack 280 terminals.
- You'll find a smattering of Sealed Metripack 280, 480, & 630 terminals in the TBI harnesses.
- Power window and lock switches for our trucks are GM pin terminals that are fairly hard to find.
- Many of the ECMs used Micro-Pack 100 connectors.
Most Delphi terminals continue to be available but the connector shells go obsolete with fair regularity.
Many of the less common connector shells have an extremely large minimum order so be nice to the outfits that are selling smaller hobby quantities of them. Some outfits like McMaster Carr, Waytek Wire, Mouser Electronics, and Allied Cable generally sell to businesses but are willing to sell to the public if we behave in a reasonable manner. You are not a highly profitable part of their business you are low margin PR. Keep that in mind. Nuff said.
Reasonable prices on Delphi; Metripack, Weatherpack, Packard 56, and Packard 59 as well as a selection of Deutsch DT, DTP, & DTM series.
The Electrical Depot is the only small outfit in my arsenal. He has good prices on quality Delphi terminals & shells along with Delphi crimp and extraction tooling. Ratcheting Dellphi 12085270 & 12085271 or their less expensive House crimpers HT-10 & HT-11 will handle most open barrel terminals in two operations (conductor then strain relief on the insulation or seal).
If you know the part numbers or at least the terminal family and metric wire size Mouser has a huge selection of Delphi, Molex, and Deutsch connectors and terminals. The Mouser website is easier to search than Digikey or Newark and generally less expensive than Newark. Newark generally has bloody everything but they're like McMaster Carr and Grainger... you'll pay for it.
SXL Crosslink Polyethylene jacketed wire called for in the GM wiring diagrams.
Spools as small as 50'. Waytek and Delcity also have some Delphi connector shells and terminals.
Allied Wire And Cablehttp://www.awcwire.com/productspec.aspx?id=type-sxl
Shorter coils of SXL, GXL, & TXL wire more suited for small projects... http://www.wirebarn.com/