I think the Jetstreme 2 used the Mectron 3 or 5 burner, and it was the Mk3 that used the R40....others will know better than me.
The first Perrymatics used the NuWay ZL series burner.
John
Perrymatic Ltd went out of Business many many years ago, the production was taken over by Benson Heating and then Halstead but the Perrymatic name no longer exists the Mk2 was a very inefficient boiler and will by now have had it's day it would be best replaced with a Grant Vortex!