Monark dual springer top bracket id

[KelRob]

Hi,

This might have been posted before, what years did Monark use the "Y" top bracket on their dual springers? I have one on my Monark Firestone.
I do not have the id tag, DARN, so I do not know when it was built. The bike was complete when my dad purchaced it in the late '80's but we lost the tag.

Thanks,
Kelly

 

[barnbikes]

My '52 has the Y bracket on it.