My stock  3 SPEED speedo gear worked in my T-5. (66 coupeV-8)
I recently replaced my speedo cable and it was just a little longer than the stock one. (this is a good thing!) Gear is EZ to replace on cable.
6sally6

Do you intend on upgrading the instrument panel in the future? If you do speedometers nowadays don’t use cables.
Mine runs off of a VSS output.

TKOPerformance wrote:

Rudi wrote:

Do you intend on upgrading the instrument panel in the future? If you do speedometers nowadays don’t use cables.
Mine runs off of a VSS output.

That's a good point.  I stayed mechanical, but will undoubtedly switch to a VSS based one at some point (should have just done it when I did the swap).  VSS based ones can be calibrated, so no gears to swap now, or if you ever change rear tires or rear gear ratio.  Typically more accurate too.  You also may need a VSS signal if cruise control is in your future plans. 
 

Other speedo options are GPS enabled makes, very easy to calibrate.
 Even though VSS can be used on cruise controll some are using magnets on the drive shaft, as is mine.

Excellent Guys, thank you!  Im ordering a C4 Cable......

NEXT QUESTION:

WHICH YOKE????  Do I have to order a T5 Yoke? is there a Proper Conversion Yoke? Or can I use my 4spd Yoke (been reading and lengths are an issue)

I bought a conversion yoke that allowed me to use my stock C4 driveshaft.  Well, until I took the shaft to the driveshaft shop and asked them to balance it and they asked if I liked the car it was going in and wanted to keep it.  Long story short, my stock shaft had some kind of vibration damper on it that used bonded rubber and a cast iron weight.  It was decided it was dicey at best, so I had the shop just make me a new shaft.  With driveshafts of this age that's something you should probably at least consider, especially if yours is rusted, pitted, etc.  A new steel shaft built and balanced took less than a week and cost less than $250.  Money well spent.