Looking at Lionel's website, the worm gear on the drive shaft appears to be different.
Here's the drive shaft for the Legacy EM-1:
By the way, a simple way to fix the coupling if it comes loose is to knurl the end of the shaft and press the coupling back on using an appropriate tool. I think it was after about six years of heavy use that the coupling on my TMCC EM-1 came loose; after the coupling was fixed this way (by the late Mike Moore of Trains and Toys of Yesterday in Morton Grove, IL), I've continued to run the engine heavily for another 11 years and counting.
The TMCC EM-1 has terrific detailing, fantastic sounds, and runs great. It could pull out tree stumps. I've been running mine heavily for 17 years, and it still looks, sounds, and runs like a champ. It remains my favorite engine in my fleet.
Cheers!
Keith
