Yes the donut is the torque converter. If you look on the converter you should find a allen head bolt(on the outer edge)...maybe 6 mm and you need to remove that bolt and let the converter drain...Yes it will be easy for you to reassemble the torque converter on a completely assembled transmission. You just slide the torque converter back on the transmission and make sure the 2 tangs go into their slots(the torque converter when it is all the way on the shaft should be back behind the outer edge of the transmission...you can see the slots next to the shaft by looking in the transmission before you slide the converter on.. then when you slide the transmission back up against the engine and install the bolts don't tighten them...leave them loose and install the 6 bolts by turning over the engine(always turn the top of the engine toward the driver's side of the car) and line up the plate with the torque converter. After you get those 6 bolts in then you can tighten up the other bolts...Good Luck Jim

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James A. Harris