Equipment In Transit

1960

EIT plates were issued A-00 format at first. They were dated individually until 1963.

1963

This was the first year for stickers on EIT plates.

c. 1973, reflective

The format then switched to AA-00.

c. 1984

Basically the same, but not reflective.
March 1983

This is the only EIT plate I've ever seen with SLOTS instead of holes.
March 1987

Still chugging along with the AA-00 format.
March 1993
April 1998, first-generation 3M sheeting
March 2002, first-generation 3M sheeting
March 2004, Avery sheeting

This format ended at YZ-99. (Z series is reserved for In-Transit Empty)
March 2007, second-generation 3M sheeting

This is the new reverse format. It'll probably last for many many years.