Someone on this board may have an answer for you... sorry , but I don't. You may wish to check out the "Detroit Diesel" group. They will
have an answer for your question. The site is a Yahoo Groups thing at: http://autos.groups.yahoo.com/group/DetroitDiesel
You'll have to join to post, but you will find a good bit of DD specific information.
I can add that the reason the MUI injectors stopped in 87 is likely due to the introduction of DDEC electronic injectors.
Good Luck, JR