That is the oil metering disc from a hydraulic lifter. Yep, but HOW? I've had a lifter explode when a pushrod got shoved down after a timing chain snapped and valve tried to fornicate my piston. But it left a lot more metal all over. Well we really don't have much information to go on. All we know is it's a 340. Why is the oil pan off? Is there other debris in the pan and this is the only piece the OP doesn't know? Was there a failure? Prior rebuild or repair? The last 340 was produced in '73 so chances are unless it's been stored somewhere for the last 30+ years it's had some work done to it.
"Follow me the wise man said, but he walked behind"
'92 D250 Club Cab CTD, 47RH conversion, pump tweaks, injectors, rear disc and hydroboost conversion.
'74 W200 Crew Cab 360, NV4500, D44, D60 and NP205 divorced transfer case. Rear disc and hydroboost coming soon!
2019 1500 Long Horn Crew Cab 4WD, 5.7 Hemi.
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