Yet another T-5 diagnose this/thatquestion...

Two words - Bad Syncros.

I don't know how you feel about the DYI thing when it comes to gears, some people don't like the idea of working on transmissions. If the DYI transmission fix idea isn't something that you would rather leave to someone else, here are some resources:

See http://www.ttcautomotive.com/English/onlineorder/product.asp to download a FREE service manual for T5 or Tremec 3550
You will need the Adobe Acrobat viewer which is also a free download – http://www.adobe.com/products/acrobat/readstep2.html

See http://www.hanlonmotorsports.com/ or http://www.ddperformance.com/index2.htm for parts

A T5 rebuild kit with syncros, bearings and other small parts costs about $160. It does not include any gears or shafts.

http://cartapes.com also has a video on how to rebuild your T5 or Tremec. It costs less than $20, and is worth every penny of it.

I did a Tremec 3550 rebuild, and it wasn't that difficult. The video was an immense help, and I would recommend viewing it. At $20, it will give you an opportunity to look and decide for yourself if you think that it is something you want to try to do.

You will also need a magnetic base and dial indicator to measure the endplay ($20-$40). http://www1.mscdirect.com/CGI/NNPDFF?PMPAGE=1290&PARTPG=NNLMK32

The tricky part is that you will need some shims to adjust the endplay in the two shafts: the new bearings will change the clearance. There is no way of telling what it will be until you get to the point that it is time to measure and check the clearances. Halon has the individual shims if you can wait for them. If you can't afford the wait, the auto parts store can sell you some shim stock and you can make your own, or have a machine shop make them for you. The shim stock comes in brass (easy to cut) and steel, in varying thicknesses. That's where the dial indicator & base come in - there is no way to get the clearance right without it.