There are no FRA-compliant DMU's except for the ancient Budds that can board at *both* high-level and low-level platforms. The only high-level boarding domestic make, Nippon-Sharyo's used on S.M.A.R.T. in California and Union-Pearson Express in Toronto,
has no door traps for boarding at low platforms because of the placement of components on the undercarriage...meaning they can't be used anywhere on the Rockland Branch. And Nippon-Sharyo has since exited the U.S. market, so if they're even for sale anymore they wouldn't qualify for Buy America. The
various Stadlers in-use stateside are all for 8-inch platforms and can't interface at all with a full-high like
Brunswick.
The All-Earth RDC's are literally the only piece of equipment that would work on a route like this, being
ADA-compliant on the interior (unlike antique-condition RDC's) and able to board at full-highs or lows with their door traps.