To be honest, I've never heard of that. All of my early .44/.44mag and .38/.357 dies were Hornady/Pacific, and none came with a spacer washer, but that is a darn good idea IMO. I bought mine in '82 BTW.
Redding sells them, and so does RCBS. I'm surprized there wasn't a spacer in your die set. You might try calling Hornady and see what they say. Besides, the girl who did their answering machine recording has a real sense of humor.........
Am I missing something they are the same straight case one is slightly shorter. There is no shoulder or issue with adjusting the die off of the shoulder and I am not aware of any dies that will size the head area in front of the rim. just set the die up to where its almost touching the shell holder and re-size both cases.
Len
Never post or reload on 1st getting up! In the shower I realized you must be referring to the case crimp. Sinclair International sell various spacers. I just use a second set of dies.