Had a look at the Rares ones on the net and wondered how you fit them, they dont seem to have the thread for the tools.
The reproduction ones don't have the centre bore threaded to 1 1/8"UNF. Instead, they have three holes tapped to 3/8-24UNF on a 2 13/16” (71.44mm) PCD, just like a red motor balancer. The reproduction ones tap on similarly to the original ones, using a block of wood to protect the face of the balancer. When removing the reproduction ones, you use a three-legged puller (available from SuperCheap) instead of the original "bolt in bolt" type puller.
Also there is talk of narrow and wide ones, what size are what?
These are Rare Spares part number 7401305 for the wide-belt FX/FJ (PowerBond part number HB17B-N), suitable for a 13A belt,and 7408676 for the narrow-belt FE-EJ style (HB1049-N) for an 11A belt. Ross Tuffbond also make a balancer, though it needs fan modifications to fit a grey.
Is it ok to fit old ones if they seem OK?
Yes, but it is always a bit of a gamble... the old one can be buggered too
. Look for loose rivets, and a lip cut on the shaft by the timing case seal... discard those ones.
Cheers,
Harv