Will a Series I brake booster work for the conversion?

G’day guys,

Am looking at doing the brake booster conversion. Most of the articles I’ve seen have mentioned the Series III booster. I’ve got both series I and Series II boosters hanging about - will either of these work for the conversion or are we locked in to Series III? Could another model car work - any suggestions? Or a universal one?

Cheers mates

Just some extra info for anyone looking:
SI boosters seem to have the bolts in a different location to the SIII - the SI have a bit more space between them. Most of the gaskets and images of the conversion I’ve seen online are of the SIII with the smaller gap.

We have a few SI and SII boosters lying around, and only one SIII which is in use in a '75 XJ6. We’ve found the the rod can be taken out of the SIII and put in a SI booster which will now fit in an XJ40.

Just found this thread which mentions other vehicle boosters being used:

Yes, Series I brake booster can be used successfully in the conversion. Here is further information on the matter: https://forums.jag-lovers.com/t/xj40-vacuum-brake-booster-conversion/286741/31