Difference between part # prefixes?

I am ordering plane bearings for my 81 xs400 special and would like to know if the 1l9 will be the same as the 12r. The “suffixes” are the same.

It just means that the part number carried over from a previous bike. 1L9 is the prefix for my 76 360c. Lots of parts that I buy have a later prefix that was used with the xs400s.. The later bearing may have oil holes in them where as the 1L9 ones may not.. I cant remember.

Good luck with the rebuild, and finding new connecting rod bolts. I had to scour the earth to find some.

Not sure about why the part prefixes are different. I had no trouble buying the exact bearings for my 81 direct from Yamaha using the chart above and the formula from the manual. The part numbers were exact. I double checked with platigauge to make sure the new bearings were right.

New Haven Mike is 100% right: the connecting rod bolts are the real problem to source.