Used an A2Z disc brake adaptor... but had to modify the front plate slightly to fit the cro-mo rear dropouts. A2Z is designed for the larger flat aluminium dropouts. A bit of filing with a hand file and it fits!
I've always wondered if the Noleen piggyback made much of a difference! Also, what about the aluminium rear triangle? Mine is the chromoly rear end and I've always wondered if the alu rear end with extra pivots made much of a difference?
Finally got my repaired and powder coated main frame back and the old RTS is almost finished! Just need a front derailleur to get it back on the trails. Drilled larger holes in frame cable mounts to allow full length gear cable housing. Finished fitting discs. (One day I'll get around to...
I have a 94 RTS-3 which started as a Purple frame... which was 7005 series aluminium. I had the frame replaced under warranty after a couple of years - the replacement frame they gave me is the same colour as yours and was 7005 series aluminium as well. I think 6000 series was the better...