So i'm driving my car and i shift into 2nd, tach it up to about 4 grand (or a lil more) and go to shift into 3rd and its like it just isn't there, so i try 4th and that one grinds...i let out my clutch, push it in and try both gears again but i get nothing...so 5th is the only option.  Lately i can feel a slight catch of 3rd every time i shift into it...any ideas? my tranny is a t3650 for those who dont know.  

Sounds like a broken 3-4 shift fork.  Congrats on one too many powershifts without a good shifter.  

Well i only bought the car about a month ago...and i realized it was doing it about two weeks after i bought it. I hardly ever powershift in my car...but it didn't do it when i test drove it although i am finding out that it occasionally happened to the seller now  

Time to rebuild.
Bullit proof it while your at it.
The expense is worth it.  

Thats what im going to do...along with a better clutch and a short throw shifter!! I'll be kickin ass and takin names in no time!  

Dont waste your money on rebuilding the 3650 sux upgrade to the tko500 or tko600 they run about 1800 you can find them on varios sites.The 3650 has plastic syncros and weak internals while the tko"s can handle upwards of 700hp.Upgrade the shifter to a mgw they are better than the others and it might resolve your problem as well as make sure when shifting to third palm it up instead of slaming it it will line up the gears better I have had friends complain of the same problem and that was what it was they were trying to kill the shifter.Hope this helps.I have 2 04 mustangs ONe is a steeda q335 that was completed into a q400 by steeda in pompano beach florida and a saleen s281 #39 also a manual tranny both 3650"s so I have played with lots of shifters and mods to the tranny and rearends on both.