Fj front engine mounts

[Pheasantplucker]

Hi All,
Picked up a spare motor over the weekend, a freebie, no idea of condition but parts missing and stored badly!
Noticed the bush in the front engine mount has corroded and broken a 20mm section of the mount making the cases useless.
I've noticed on another motor I have the front mount casting looks improved, thicker with ridges cast in.
Here's the question, when did Yamaha introduce this stronger mounting?
My 1tx has a thinner mount, any ideas?
I'd like to avoid the slimmer mountings on any other engines I find as I'd like to hang a fj motor in a Harris frame.