Okay.
I'm only going to reply in this thread because you created a duplicate thread here :
http://www.delica.ca/forum/transmission-chaos-6903.html
and everyone knows I'm a stickler for people creating multiple threads on the same thing or every little question they have.
With that said, here's my armchair synopsis. Throw it at your mechanic if he agrees.
Check the simple things first. I've found over my years that some shops will automatically assume the worst and start working at that, possibly skipping over something simple that could save money and time.
Linkages at the shifter, in between (stuck ?) and at the transmission.
Like I said in the OTHER thread of yours on the SAME topic.
jfarsang wrote:Disconnect the shift linkage at the transmission
Jack up the Delica so that ALL four wheels are evenly off the ground and the whole vehicle is supported by either a hoist or proper weighted jack stands.
With all four wheels off the ground and the shift linkage disconnected at the trans, have someone push the clutch down and go through the shift points at the transmission directly.
That will tell you whether or not it's the linkage (between trans and shifter) or transmission internal/ like Andy said.
And try not to be PISSED !!!!
Nothing good will come out of it. By being upset or angry, you may miss something or screw something up. Not good.
Just keep a cool head, take a step back and look at things from a different perspective. There's more ways than "PISSED" to look at things.
Good luck

If no reverse engagement at all, good forward engagement and nothing in reverse then it's the forward planetary.
In the pan, you'll likely find fine metal on the magnet and some glittery chunks scattered about. The planetary isn't something you'd want to just replace with doing an overhaul on the tranny. At least do a reseal with rings, if not the clutches too.
Or better yet, just get a used one from Glenn with a warranty.
Of course, nothing can be determined with 100% certainty over the internet.
The mechanic looking at it will figure it out.
Transmissions are a different breed that takes a certain skilled mechanic to work on them properly.
Make sure yours is one of them before attempting to rip into the trans.
Remember. Simple things first. Like the transmission fluid. Before you do anything, check the current level and see where it sits. Also check the smell for burnt oil and once you've done that, then drain and check for metal flakes as I mentioned above. Once that's done, then go over the shift linkage from front to back like I said above as well.
More heads are better than one and I think I've laid out enough options for you guys to get a good start.