This article has some RA-103 restoration notes that may be helpful in a general way.
http://antiqueradio.org/DuMontRA-103Television.htm
I assume the -D flavor has some differences, presumably not huge or they would have gone to a new model number.
Have fun. DuMonts are my favorite sets to work on.
Phil Nelson
Phil's Old Radios
http://antiqueradio.org/index.html