The stock length driveshaft will work with no changes.
Depending on what model TKO you get, you can use the stock clutch disk and driveshaft yoke. See
http://www.ttcautomotive.com/English/products/TKO.asp for more information.
You will definitely need a new bellhousing.
DIY transmission swap:
Labor time: by yourself, first time - 4-6 hours from the time the car gets up on jackstands until the trans sits on the ground & the bellhousing is off. You'll have about the same amount of time to get it reassembled & back in service.
You need both metric & US tools to do the job, the body bolts are metric & the trans mount & engine bolts are US.
The rear driveshaft bolts are 12MM, 12 point and require a first class box end wrench (ring spanner if you are English or Canadian) to remove them. Don't get cheap here or you will regret it. I set the emergency brake and apply a foot to loosen the bolts. Notice the paint marks on the driveshaft & rear end flange: align them the same way they came off. If there aren't any marks, get out your paint spray can & make your own marks.
Be sure to drain the fluid before you remove the trans or you will get to wear it. The best time to do this is before you remove the driveshaft. Have a catch pan in place to get the fluid that comes out of the trans when you pull the driveshaft yoke out. T5's take a good grade of ATF, Tremec 3550 & TKO use 2 3/4 quarts GM Syncromesh at $9+ a quart.
The speedo cable pulls straight out of the adapter, don't pull the clip out of the adapter. It re-installs the same way: push hard on the cable. You can unbolt the speedo cable adapter and pull it out of the trans: this may be the easiest way. Then you don't have to worry about pulling the cable apart. I have had the cable housing separate from the metal sleeve when I it pulled it out. If you do unbolt the adapter, then cover it with a plastic zip bag.
The H pipe will have to come off and the studs are likely to be very rusty. Soak them with PB Blaster or WD 40 overnight if possible. When you re-assemble the H pipe & exhaust bolts, use lots of antiseize. That way they will be easy to remove next time (yes, there will be a next time!). Use care in disconnecting the O2 sensor wiring that you don't damage the clips that help hold the connector halves together. Be sure to tie wrap (zip tie) the wires out of the way when you re-assemble them.
Identify & mark the neutral safety switch & backup light switch wiring. The connectors are different, but it helps you to get them back on it the right places.
Look at the rubber on the rear trans mount and replace the mount if it is oil soaked or deteriorated. The same goes for the rubber crossmember bushings.
If you have a T5, you may be able to remove the trans & re-install it if you can bench press the 75 lbs that it weighs. If 75 lbs is too heavy, don't hurt yourself, get a trans jack. If your car has a Tremec 3550 or TKO, you will need a helper or trans jack because it weighs 100 + lbs. I built a trans jack from 2x2 angle iron, some swivel casters, 2x4's, 2x6's and a cheap floor jack. PM me if you are interested & I will send you the photos (8 MB) with the write up.
While you are at it, replace the stock cable & quadrant if it is still present. When you buy the cable & quadrant and maybe a firewall adjuster, make sure they are all the same make. That way you have some assurance that they work together. I have a FMS quadrant & cable, & have had no problems with it. The FMS adjustable cable doesn't stretch and operates smoothly. The only thing is that you have to get under the car to make any adjustments. A firewall adjuster would help here to make the fine adjustment.
5SpGT has a very good write up too. I highly recommend that you read his tech note as well.
