I’m not sure what they did in 99 –. There is a good chance it is a Yamaha TMXx carb. In 99 it looks like they still used the plastic inlet needle valve assembly. The plastic inlet would make it look like a TMX – but yet the slide, in the picture, looks TMXx. A good indication is the slide - if it is metal – the carb may be an OEM TMXx. On current models they have changed the inlet needle to brass and raised the fuel level about 10mm. You will find (at least for current models) that the main hex jet and long pilot jet are interchangeable with standard TMX jets. The slide is metal and the needle has the right tapers – to work with the Yamaha. So – you can probably buy mains and pilots from any big carb dealer to fit a TMX but the needle and slide should be OEM for the TMXx. The OEM carbs on all the major brands are superior to the standard TMX. But – a good turner can make the TMX work very good as there are more parts available – it’s just that the OEM style is more precisely made. But – with OEM you are limited to what that brand has to offer.
Bob Hogg