m40 connecting rod 3 is same and the 1 is different

[markus_74]

hello,

i have open my engine and take inspection.

I found that 3 of my connecting rod is same with the bottom of it stamped "C4"
the other stamped in the body is "B" , 1719 411, 210

the other one that is different at the bottom stamped "B5" and the body stamped 3E and 1715

does different connecting rod cause my engine idle tremor?

any member here has a good pics of his conrod so I can know which is original?

thank you
markus