Are you asking about modern DMUs? Or can we include Budd RDCs here? I'm sure that for the right money, any of the current builders could equip their offerings to be used as DMUs or locomotive pushed cab cars. That is, assuming that they are built to the current FRA standards, for use with conventional equipment.
In the past, Budd RDCs were used as cab cars on the old Boston and Maine lines now operated by MBTA. Starting with some bad order cars that operated as locomotive hauled coaches sans driveshafts, transmissions and other vital parts, MBTA eventually had many Budds rebuilt as conventional coaches and cab cars. The early conversions used a special 12 to 27 pin MU adaptor cable, allowing the use of the original Budd control stand.