I'm afraid I'm not that familiar with REOs or the 510s used in them. I did own one Grand and some Woodvils, but never really used them much. All but one cocobolo Woody got PIF'd, and the woody sits on a shelf about 600 miles from where I am right now.maybe @Rossum can answer that or post where reo followers will see it.
The mods I favor use a very different 510, which I know intimately and have plenty of spares for.