You can try HQT, but they may just direct you to Sharp Industries, like they did with my parts needs for an Alliant vari-head. REM Sales in Philly is the importer of Alliant, but they will have parts drop shipped from Sharp in So Calif, or at least they did me.
This has been posted several times, but chances are your mill head parts will be interchangeable with those from a Sharp mill and Sharp will supply them. As I recall mine is a model 42VC and was mfg in 11/84. I got a manual for an RT2V which is slightly newer, but mfg dates overlap. There do not appear to be any differences in parts from what I can see. The manual is available from REM Sales for about $40.00 and is nicely done and worth it IMHO with very nice double page parts illustrations.