Even better question, which years of rectifier will fit my 1980?
To answer your ? Yes.It reletively easy to find and sells for about $35.I have one on my bike.
Check on mikexs ,bike bandit,motorcyle super store.The part is universal and fits other models other than the xs400.I realy don't know what brand they are.I know that I have one on my bike its unmarked.Also good rectifier on google there will be many search results in which the part will come up.