assuming the ratios are the same obviously.

a friend of mine shattered third gear in his WC t5. took out the countershaft with it. i have 2 NWC t5's in pieces laying in storage.
will the NWC countershaft go into the WC T5 and work with the WC main shaft gears?

or is a countershaft available anywhere? hanlon seems to only have third gear and not the countershaft

 

The T-5 doesn't have a countershaft. The countergear doesn't mount on a shaft, like 4-speeds did; instead, the bearings for the gear are large unit bearings that mount in the case.

So I'll assume you're talking about countergears, not countershafts.

No they are not compatible. That's one of the specific design changes incorporated into the 2nd design T-5.

Yes the countergear is widely available. Any place that carries manual transmission parts will be able to get it. You might want to try these guys www.rsgear.com