Wrong gas was put in my truck

I have a 95 chevy 2500 truck, 200,000 (about) v-8
I Let a friend borrow my truck and some how he put diesel fuel in it drove it a couple blocks untill he seen white smoke, we drained the gas and put gas treatment and 91 grade gas and drove it, it drove okay except for a pinging or rattleing, what damage should I expect? And what shoud I do?