Danny what does 1st undersize mean ??
there are usally 3 options for bearing size when buying them othen marked "std " to indicate they are standard size then there is " -.010 " or "-0.10 " for 1st undersize and "-0.020" or "-0.20" for 2nd undersize.
wayne - as metal will have been removed from the cranck if it has had to be reground hence reducing the diamiter of the bearing journal slightly hence new bearings can be bought in smaller sizes. not larger ones it's pistons that come oversize as metal is removed from the inside of the bore and increases it's diamiter tho often not the case on more modern engines as you'll overbore by anything fro 60 - 300 thou and pres liners in and use std size pistons
often you can just polish the jounals up with a bit or rope over some 2000 grit wet and dry and spinning it around for a bit and chuck std shells back in
