The 349 box you have is the better box. The pinion shaft on yours has 121 needle bearings as opposed to the 350 box which uses 3 bronze oilite bushings. To me the needle bearing box is easier to turn the wheel while the car is sitting still. The main issue manual boxes have is the top of the pinion shaft where the three teeth are. The center tooth will have wear on both sides of that tooth because that is where the steering is most of the time, straight ahead. If you take a die grinder with a stone bit and reface that tooth smooth again the box will operate smooth as silk when you put it back together. I've done a bunch of these like this with great success.