Here are images of some of the changes to dies and the coin varieties that arise for Australian 5 cents from 1966 onwards. I say some, because I may not have them all and some images I cannot locate right now.
1966 5 cents Reverse Die Type 1 (
Royal Mint London die)
- coins struck at
Royal Mint London.
Image not available.
1966 5 cents Reverse Die Type 1A (Royal Australian Mint Canberra die)
- coins struck at Royal Australian Mint Canberra
- shortened spine on forearm, top left of coin

Image - 1966 5 cents Canberra reverse.
1967-1972 5 cents Reverse Die Type 1- coins struck at Royal Australian Mint Canberra
- reverse same as for 1966 London die

Image - 1968 5 cents reverse.

Image - 1967 5 cents reverse Type 1 showing gap at bottom.
1972 - 1986 or 1987 5 cents Reverse Die Type 2- coins struck at Royal Australian Mint Canberra
- new reverse die type used part way through 1972 production run
- used for most coins struck during 1984 production run and with coins in Mint and Proof sets in 1985 and some in 1986 and said to have been used briefly for 1987 circulation coins but 1987 coin not cited by me
- Echidna design appears reduced in size so that there is a wider gap between rim and bottom of design (designer's initials) and slightly wider on each side of Echidna

Image - 1972 5 cents reverse Type 2

Image - 1972 5 cents reverse Type 2 showing gap at bottom.

Image - 1981 5 cents Reverse Type 2 showing gap at bottom and rim.
1981 5 cents Reverse Type 2a- coins struck at
Royal Canadian Mint Winnipeg
- no noticable difference in reverse die to that of Canberra except maybe the rim

Image - 1981 5 cents reverse Type 2a
RCM showing gap at bottom and rim.
1981 5 cents Reverse Type 2b- coins struck at
Royal Mint Llantrisant
- no noticable difference in reverse die to that of Canberra except maybe the rim

Image - 1981 5 cents reverse Type 2b showing gap at bottom and rim.
1984, 1986-2010 5 cents Reverse Type 3- coins struck at Royal Australian Mint Canberra
- design appears to have been increased slightly in size and designer's initials re-engraved apprear slightly larger than 1966-72
- the gap between rim and bottom of design (designer's initials) is smaller than Type 2
- circulation coins for 1984 Type 3 reverse appear to have been struck late in 1984 production run, no coins of Type 3 have surfaced in sets for 1985 and there appears to be an even mix of Type 2 and Type 3 reverse in mint and proof sets for 1986, all coins inspected for 1987 have been Type 3

Image - 1984 5 cents Reverse Type 2 showing gap at bottom.

Image - 1984 5 cents Reverse Type 3 from circulation showing gap at bottom.

Image - 1986 5 cents Reverse Type 3 from set showing gap at bottom.
1991-1994 5 cents Reverse Type 4- coins struck at Royal Australian Mint Canberra
- reverse features a large designer's initials at base of design filling most of gap between rim and design
- this large SD variety can only be found on circulation coins (coins from sets have Type 3 Reverse)
- both Reverse Types 3 and 4 can be found in circulation coins with Type 4 very scarce for 1994

Image - 1991 5 cents Reverse Type 4 from circulation.

Image - 1991 5 cents Reverse Type 4 from circulation showing gap at bottom.
2002 - ? 5 cents Reverse Type 5- struck at Royal Australian Mint
- possibly another variant of Type 3 Reverse but designer's initials appear finer and the spines on either side are further apart than for Type 3
- this type may appear on other years from as early as 1990 and as late as 2007

Image - 2004 5 cents Reverse Type 5 showing SD at bottom of design.

Image - 2004 5 cents Reverse Type 3 showing SD for comparison.
2007-2009? 5 cent Reverse Type 6- struck at Royal Australian Mint Canberra
- reverse redesigned with design larger and SD smaller
- spines at top of coin almost touch rim and SD is tiny compared with all other types
- Type 6 reverse appears on a small number for 2007 circulation coins struck late in the production run for 2007 and appears on all 2008 circulation coins but a mix of Type 3 and Type 6 can be found in Mint Sets. Type 6 not yet sited for 2009 circulation 5 cents or in 2010 Mint Sets but can be found in 2009 Proof Sets

Image - 2007 5 cents Reverse Type 6 from circulation.

Image - 2007 5 cents Reverse Type 6 from circulation showing tiny SD and gap at bottom.

Image - 2007 5 cents Reverse Type 3 from circulation for comparison of SD size.

Image - 2008 5 cents Reverse Types 6 and 3 showing SD for comparison.