So I just finished rebuilding my center support including a new torque tube "donut" and differential prop shaft seal. Time to top-up the 80W-90 in the differential. I unscrew the filler plug and prepare to add the oil - holding up the bottle with the cap still in place to decide what angle to hold it at ,before adding the oil, to make sure the stinky stuff won't spill all over. And then, PLOP, the plastic bottle cap falls into the hole and deep into the differential. I lay there, blinking, trying to evaluate the consequences. This should be pretty easy to get out, right? Nope. I put about a half hour into that strategy with various instruments before giving up. I thought about filling it with oil so that the cap will float out - but an experiment shows that the cap doesn't float in gear oil. Next I wonder "is it really that big a deal?" I think it probably is and I'm thinking I really should remove the cover and get it out of there. Anyone want to try to talk me out of it?