data bbb;
set aaa;
length brand $50. num $50.;
x=strip(kreverse(y));
pos=indexc(x,'0123456789');
if missing(input(substr(y,length(y)-pos,1),best.)) then do;
brand=substr(y,1,length(y)-pos);
num=substr(y,length(y)-pos+1);
end;
else if not missing(input(substr(y,length(y)-pos,1),best.)) then do;
brand=substr(y,1,length(y)-pos-1);
num=substr(y,length(y)-pos);
end;
run;