how do i know if i have a mopar performance distributor

Take a look at the mechanical advance flyweight springs. If they are both very lightweight springs with round loops on both ends (or if there is just one lightweight spring in total, no second spring) that's the MP setup: it dumps all the mechanical advance in real quick off idle. Fine on the track…not so hot on the street. Street-type distributors have one heavy and one lighter spring, often different colours, and the heavier spring has an elongated loop at one end so it doesn't become active until the lighter spring is stretched.

Also, if the part number tag is still present, and its number starts with a "P", that's a MP item.