Hi Malcom , I own a Myford ML4 ,they're a good lathe,but there not in the same league as the ML7/ super 7's but are capable of turning out accurate work , I can hold a 0.002 thou tolerance during a batch run .
When I purchased my lathe I was of the opinion that all Myford parts would be interchangeable between the Myford range ,I had grand visions of fitting a screw cutting gearbox amongst many other accesories ,but unfortunately this didn't materialise because of the ML4's bed and head stock design .
The good news is that some Myford items are interchangeable ,face plates ,3&4 jaw chucks , screw cutting gears will fit but some may need to have a bush fitted to the internal diameter of the gear ,number one morse taper drill chucks fit the tail stock ,quick change tool posts are also available from various suppliers ,RDG tools ,Chronos to name a few .
I've had many hours of enjoyment on my ML4 and gave carried out several modifications to improve things further ,but these mods have been carried out sympathetically as I'd hate to see a piece of Myford history being butchered ,if you need any help ,send me a message or email and I'll help and advice where I can .