If that was the b3 rod wouldn't there be no reverse gear (or reverse all the time)?

It's most definitely one of the thrust pins from either side of one of the bx pistons and not a good sign.

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1982 300TD 210K miles ("The Replacement" aka "The Anvil") - SOLD
1979 300SD 245K miles (never ending project)
2007 Pinarello F3:13
1995 Ducati 916 (SOLD, sniff)
1999 Ducati 900SSie (SOLD)