Stock timing, 93 octane and I still get detonation????HELP!

[StangDan]

I have a serious problem. My timing was never altered from stock, a 72 year old woman owned my car so I know it wasn't touched. My problem is when under moderate acceleration at about 3000 RPM's I get a pinging from the engine, NO MATTER WHAT OCTANE I use. I have a stock 5.0 with A MAC cat-back and MSD 6AL, that's all, it pings with or without the MSD connected. Plugs are gapped at.045. The only thing that I can think of is that I switched over my car from a AOD to a T-5 and I left the stock computer in the car. My car has 80,000 miles on it, 68,000 of which were pampered by the old lady, too bad I can't say the same for the other 12,000, but that is STILL no reason for the Detonation,. Please Help I am going nuts!!!! Thank