I guess the thing to remember is Stevie used a single coil guitar, a strat. Also the neck was changed to an older model style. I guess what I'm getting at is everything on or in the guitar is going to give it it's own character. Everything from how old the wood is (the older, the dryer and usually lighter), guitar shape, control electronics and wiring, string gauge ( he used a very heavy set), etc., then your guitar cable, any inline devices, your amps and speakers. Stevie would, on some cabinets use tape across the center of the cone area on the grill cloth (outside) to decrease high frequency beaming. Usually just an "X" shape in the center of the speaker area. I live in San Antonio now but, when I lived in Austin I saw and spoke with him a couple of times about his set-up. He had other guitars and amps, I saw him with a Dumble once, but his main guitar was a single coil Stratocaster. I don't remember if he changed any out with older or newer pick-ups of the same type but, even this would change the sound. However, his sound....well he could get it with whatever he played because it's all in the hands, head and heart anyway.