The truck carries the parts that fail most often on openers from this era: chains, sprockets, drive gears, capacitors, and logic boards for the handful of brands that dominated garages built in the 1960s and 70s. What it doesn't carry is every obsolete part for every discontinued opener model. If your unit is a specific older model that's been out of production for a long time, the part sometimes has to be ordered, and we'll tell you that up front rather than let you wait around on the driveway.
We also carry full replacement openers on the truck for the cases where the motor's gone or the unit predates current safety standards enough that a repair isn't worth doing. That decision gets made at your garage, based on what we actually find, not guessed at over the phone.