Different size main bearings

[Command52]

I understand that there is different thickness bearings, But are the rod and main bearings different as far as the width ect in different year engines. I thought I read here about the rod numbers make a difference on which bearings to use but I cant locate that now. Maybe there is a way to tell that someone can explain to me . I want to order the correct bearings, Thanks Billy

[tst]

main bearings were all the same except for thickness, rod bearings had two different type, you id them by the part # on the connecting rod,

[Command52]

Thank you for your help