The casters I have are from
www.castercity.com chromed covered caster part number # FEH-RD2XF-GR2
with corner brackets that need to be grind/filed down to fit in the inside base corners - part number # MB90
that is what I used on my Nichol Kola... the chrome fender looks are close (better cause they're chrome) to what was used orginally and help dress up the bottom without going over board.