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I'm going to agree with almost everything Rumble said.
That being said I believe that there was actually three different windage trays. The 340 tray, the slotted tray and the third tray was a 360 tray that got dropped in favour of the slotted tray. I could be wrong but I doubt it.
As for the back problem I totally understand I was hit by a semi back in 1991. I have two herniated disc from that. And I'm not about to let them use a knife on them. That is what chiropractors are for.