Mystery 18-pin and 10-pin Molex Plugs
Well the second one looks a lot like the below, which I found using the search terms "molex catalog connector" and then browsing the Mini Fit Jr. range as suggested in your question.  

You can browse their PDF catalogue.



This is from page 63 of the PDF above, their reference "MX10 E-63".  It is described as:


  4.20mm (.165") Pitch 
  Mini-Fit Jr.™ Crimp Terminal Housing Receptacle 
  5557 Dual Row


This comes in an 18 way part also, which might be your first image.  Shopping questions are off-topic but you should be able to find more with these details.