Years of Remington 870 to stay away from?

[RethaKoch]

I'm trying to get a used Remington 870 police model since that's what I'm trained with and they can be found relatively cheap. I'm not concerned about the condition, I can promise you the ones my department uses are not peaches. But I know Remington had problematic years and the 870 was an unfortunate casualty multiple times. I know not to buy new batches but which ones should I also stay away from? Specifically from the eras where wood stocks were commonly used because I'm getting into the old school look and feel. Our department has them in the armories but they're never deployed anymore, all plastic unfortunately