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In what year did electronic ignition become standard in Chevy truck engines?

Thanks

1974
The HEI system was introduced in late 1974 on some GM cars, and was used across the entire GM product line in 1975. This new ignition had a significantly higher output and longer spark duration, assisting GM meet the ever tightening emission standards.

ok thanks for the info

The Clean Air Act of 1968 mandated that all emission-related systems such as fuel and ignition had to operate for a minimum of 50K miles without being serviced. Point-type ignition systems couldn't meet that standard, nor could spark plugs once the gap eroded a little. By the mid-1970's all automotive manufacturers had to go to some sort of electronic ignition to eliminate points, and solid state ignition control allowed a higher-output coil to be used that could fire worn spark plugs effectively enough to prevent misfires. Coils for point ignition had a maximum primary current of around 5 amps, while electronic ignition coils could flow about 15 amps, resulting in a much hotter spark.
Jerry

I bought a new 'off the lot' GMC K1500 350 4 speed in March of '74, it was an HEI ignition, so early 1974 for some of the models. I was still a high school senior but working part time with the high wage of $2.50/hour. I was in heaven.

Those early ones had a nasty habit of blowing a hole through the center of the distributor rotor and firing the spark directly to the centrifugal advance weights. That was particularly true if a spark plug wire came off or the wire open circuited for some reason. That 50K+ coil voltage was going somewhere, and if it couldn't find its way to a spark plug, getting through a little bit of plastic in the center of the rotor wasn't much of a problem. GM solved that issue by making the rotor much thicker in the center.
Jerry

Jerry, didn't they also change the spark plug gap spec from .060 to .045?

Some of the HEI systems had gaps as wide as .080". The mixtures were running so lean for a while that there would be an intermittent miss at the narrower gap because at times there was no fuel to ignite between the electrodes of the spark plugs! I tried narrower gaps on some of those engines (Cadillac, IIRC) and got misfire complaints after a tune up. Once catalytic converters came into general use, they could richen up the mixture and narrow the plug gap, and still meet emission requirements.
Jerry