Transmission & Differential - Syncro Problem - Best Plan of Action??

So apparently my 3rd gear syncro is bad because when I shift into 3rd it will often pop out (not engage right) when I let out the clutch. I have known this for a couple months cause its been going on for a year or so.

Anyways I have a 99 EX, what would be my best plan of action to fix this? Have the syncro replaced? Or get a used transmission somewhere and replace it myself? I'm guessing that the syncro is pretty difficult to replace so I'd probably have a mechanic do that, but I could to the transmission myself. So how much would having the syncro replaced cost?? What do you think I should do, the problem is quite annoying and needs to be fixed.

its not the syncro with that d-series tranny i bet the CS bearing under the shaft assembly has moved outward. very common on the d-series. also people think its the syncros when they start grinding third gear but its not, the shift forks get warn down or break and need replaced.

Well its rough and it doesn't engage properly. So should I get it fixed or get a new transmission?

it really depends on how comfortable you are with taking a tranny apart. you can pick up another d-series tranny for $200-$300

Well I'm not very familiar with the transmission internals and wouldn't know if it was bad or not so I'd probably pay someone else to fix it or if I replace it I would do it myself. How do I know if the transmission is the right one, I know some will work but I want the right one, since I have a vtec motor. I've got a 99 civic EX so whichever one goes with the D16Y8 motor. How do I know if its the right one?

there is a code stamped onto the transmission that indicated which motor it came from it will say P40/B000 by the drain plug