I very much doubt that it was any more unusual than any other Triumph year!
<The valve guides fitted have the turned flange on them to keep them in the correct position. These are shown in the '79 parts book. The 1980 book shows guides with circlips. My inlet guides are fitted with a seal - not shown in 1980 book but '81 lists them as being fitted to circliped inlet guides.>
How can you be sure they are the original valve guides? . Have you owned the bike from new?
If not, and it's got more than 10k miles on the clock then there's no guarantee they are the original guides-unless you know everything about its history before you acquired it?
Replacement guides (such as those supplied by Norman Hyde) can be flanged type with inlet stem seals.
<Have I got an earlier head fitted - mine takes push in exhausts - they fitted push in exhaust pipes in 1980 only I think?>
Heads usually have a date code cast on them?
The push-in pipe system was used from mid-1972 season to 1980.
Push-over pipes were re-introduced for 1981.
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