Transistors used in System 80 games and where
MPS-U45: driver board solenoid and lamp driver. MPS-A13: driver board lamp driver. 2N5875/2N5879: under-playfield coil drivers on games such as Volcano, Black Hole and Haunted House. 2N6057 (same as 2N6059, also PMD10K40): pop bumper board and power supply. 2N6043: driver board medium coils. 2N3055: three on the driver board for heavy coils. TIP31C or SW4F013: power supply. 2N5550: power supply high-voltage section. 2N4400 (= 2N4401 or 2N2222): CPU Q2/Q3 in the reset section. MPS-A70 (= 2N4403 or 2N2907): CPU Q1/Q4. 2N4403 also appears on the power supply.
Systems
Source: Repairing & Upgrading Gottlieb System 80 Pinballs from 1980 to 1989, Part One, Clay Harrell (pinrepair.com)