When did JMJ mustang change to 1 5/8" nut?

I am looking for a JMJ mustang but I just realized that the new ones have a 1 5/8" Nut. I much prefer 1.5" and I am pretty sure the originals were 1.5". Does anyone know when they changed as I am looking for one with a 1.5" nut.

Also I would be curious to find out why they changed the width if anyone knows this?

thanks a lot!