Early version of the 3/4. You can tell by the design of the tsilstock. I have a later 4, where the tailstock has a single large nut to hold it down rather than the small ones at the front. As Porker says have a look in lathes.co.uk. Nice old machine for small stuff, and quite a few still around so you often see parts on e bay etc.
Looking at the picture you have the tumble reverse, and back gear. Looks like you are just missing the covers for the headstock and gears, which is normal. Very rare to find one that is complete with the covers. Perfectly usable without them. Do you have any change wheel gears with it? You will need these if you want to do screwcutting. Looks as though it already has a set installed so you will have power feed for the saddle, having other sizes just allows you to vary the gearing for different feed speeds and screwcutting. Good idea is to fit a handwheel on the end of the leadscrew, very useful for manual feed. Looks to be fairly complete and not to have been messed about with too much. Nice to have the original motor pulley bracket as well. Only question will be how badly worn it is. Be very careful with the spindle bearings, easy to break the caps if you overtighten them. The bearings are phosphor bronze split bushes, often in perfectly useable condition, will cost quite a bit to have replaced if they're shot.
To adjust them just gently nip up the cap on the left whilst turning the spindle by hand. As soon as you feel slight resistance back it off a tad till it's free again. Then repeat the procedure with the right hand one. Very important to lubricate them well when it's running. I have small brass drip oilers on mine. It's a total loss system so will get through some oil, mine will empty the oilers in about a couple of hours or so of use. Have fun!
Yup. Just went out and had a good look at mine. M4.
Be VERY careful with maintaining this one. Recommend you look up several VERY good, informative threads on the M.E. forum, There are a couple of doubled-up set screws in and around back gear and the head which catch people out if not fore-warned. Getting spares (think headstocks) for this baby is in the same universe as rocking horse droppings....