More valve seal confusion . 1972 750GT

[Titof]

Hi All,

I have read a number of posts related to valve guide seals and understand that there are 2 types: an internal o-ring, or an external cap (mushroom).

I have removed the head from my engine (n°750617) and found an external seal that does not look like the cap (mushroom) type, but a more standard cylindrical automobile type.
It was very hard/stiff and was damaged when removed.

What confuses me is that there is no groove on the guide itself (neither external or internal), so I assume a new replacement valve seal cap (mushroom) will not stay in place. Do I need to replace it with the same cylindrical automobile type? If yes, where would I find the correct one?

Any help would be appreciated.

Thanks,
Christophe

[Titof]

Extract of parts book, page TS Vertical Head (or Horizontal Head)

I just found that it is actually identified in the parts book as 0755.92.150 (vs 0603.92.150).

A quick search on the internet and I found this statement on another forum (https://www.ducatiforum.co.uk/threads/a ... parts.594/):

750 VALVE STEM SEALS: D=0755.92.150
The black valve stem seals with the circular springs and firm sides from the first 500 bevel twin motors can be replaced by a General Motors part GM 902 15296. These are a perfect fit on the longer exhaust guide, but need a little bit of sealant on the shorter guide to ensure adhesion.

Any ideas where to find the originals or the GM equivalents?