These solid mounts replace the rubber diode board mounts and avoid the common problem of the rubber mounts breaking and allowing the diode board to short against the front case. The threads are metric, and take the same nuts as the original part.

In addition they improve the electrical grounding of the board.

They are sold as a set of 4 for $18. If ordered with a diode board they are $15.

Some models do need these mounts.
The following engines are built with solid mounts as part of the timing cover casting, and therefore do not need these parts.

1970-1973 - R50/5, R60/5, R75/5
1974-1976 - R60/6, R75/6, R90/6, R90S
1978-1987 - R65 and R80

Read these notes on installation:
Some people have asked how the old mounts are attached to the timing cover and how best to remove them and install the new ones.

1. The holes through which the mounts pass are not threaded. The mounts are held with nuts on the other side of the front cover. These nuts can be accessed by removing the top engine cover over the starter motor area. IT IS NOT necessary or advised to remove the front timing cover.

2. The nuts can be a bit of a pain to loosen, in particular the lower, left mount (viewed from the front) can be particularly annoying to get at on some models, but with patience and a small wrench it is quite possible. I have done this by using a box wrench (ring spanner) turned backwards, through the aperature in the front cover. The nuts do not need to be turned much to get them loose.

Yes, there is not much left of these rubber mounts - they broke off when the diode board was removed.

3. The studs on the new mounts have allen (hex) heads which makes the job of tightening after installation a lot easier than the rubber mounts. Due to the fact that these are solid and have no "give , and the fact that the holes in the cover do not always accurately align with the mounts, I strongly recommend placing the diode board over the mounts as a template before final tightening onto the engine, using an allen key.