That square black box is the power transistor that makes/breaks the coil's ground path to trigger the spark like the points in an old Chevy Kettering ignition. There's a test for it to test the solid state switching function, some do do about either putting a voltage on the base or not and measuring the resistance (?????) of the N-P (or is it P-N?) junction. The power transistor is switched by ecu command, so if the ecu is not working, you get no spark....
My decision tree would be to test the function of the power transistor, and if bad, or if ecu error codes are flatline, have the ecu evaluated by one of the ecu rebuilders. If the failed capacitors didn't eat the board traces, it can be "re-capacitorized" and have the coating repaired, and work like new for relatively cheap, compared to (1) new factory - you could buy another truck for what it costs, or (2) boneyard ecu (and there's not much cross year compatibility), which may have the same failure just waiting to happen - the capacitor failure is probably going to hit most (over 50%, at least) ecu's somewhere along the way - design flaw - this a known short lived component.
Do a search on ECU repair, several documented here over the last two-three years, with links to repair shops who did (goood,ok,bad,you name it) work for people here. At the worst, a real shop can tell you up front, and probably free, if your ecu is buildable. If not, find a guaranteed rebuildable boneyard ecu and have it fixed. Car-part.com is your friend here. Search under "engine computer". My bet is one and a quarter will buy one...
