I hope I'm not raining on the parade here ...
. Entering "12V Lucas
ALTERNATOR TRIUMPH NORTON BSA MAGNETO SPARX" into the eBay
search box got me to this one
. That is not a "high output" alternator by the definition usually used on this forum's Boards - 14.5A @ 5,000 rpm (aka '180 Watts'), Lucas
RM23 (single-phase) or RM24 (3-phase) or patterns.
. Neither is it a replica of a Lucas
RM21 - that was a two
-wire single-phase alternator that produced only 10.5A @ 5,000 rpm (aka '120 Watts').
. More importantly, the RM21 and all subsequent Lucas
stators, and the patterns, embed the coils in a greeny-coloured resin, to protect the thin coil wires from vibration. So it will not be a "replacement for the unreliable "Prince of Darkness" items"; that "replacement" is likely to be far more unreliable than the perfectly-reliable Lucas
RM21 and later stators.
. It would appear to be a pattern of a Lucas
RM19 or RM20 alternator; as with those, you connect two of the three wires together to give 12V, otherwise it only produces 6V and needs the specific wiring and rotary light switch to switch the stator coils.
supplied the RM19 and RM20 from the early to late 1960's. If it's a copy of the RM20, it does indeed have a 'higher' output than the more-common RM19 but still no more than the 10.5A @ 5,000 rpm (aka '120 Watts') of the standard encapsulated two-wire single-phase RM21 that superseded it. If it's a copy of the RM19, it'll have a much lower output.
got the proverbial "good deal"
Alternatively, "if it's too good to be true, it probably is"?