6809 vs. 6809E

A question for someone with specialist knowledge in 6809s. I work on pinball machines a lot, and the 68B09E is a commonly used CPU. Unfortunately, it's getting harder to find 68B09Es (though by no means impossible quite yet). It seems that most of them on eBay are counterfeits; the last lot I bought were all fake, marked Japan on the front, but China on the back. They looked very convincing, with the markings etched very nicely, rather than printed. Unfortunately, they didn't work. Overall, it looks like getting 68B09Es is becoming harder, and I'm wondering if there's some alternative. I spent a while looking over the datasheets of the 68B09 as compared to the 68B09E. It's obvious that there's some difference in the way the timing works, but I haven't been able to come to any firm conclusions what the exact difference is, and what purpose it serves. The best I can do is that it's related to synchronization with some external devices. So - can anyone explain the difference, in terms that aren't too hard to understand? And - is there any hope of modifying a machine that would normally require a 68B09E to be able to use a 68B09?