Thx for the replies on the early grill cloth issue. Still haven't come up w/anything but will give a holler if I do. BTW, Basiklybass mentions '69s as having the later vertical pattern, which is partially correct. I have two Solarus heads, one bearing the chassis date of 5/22/69 and the other 8/1/69, which both have the earlier diagonal-weave fabric. This would pretty much support what I have consistently read that Sunn made the changeover in late '69.
Cheers!