Did you try MitsubishiParts.net as well? The fifth gear is the same as for the StarQuests. Don't know for sure on the countershaft gear. The main difference between the two is that the truck has lower 1st and 2nd.

Might try sourcing for the cars' tranny. Sounds dumb, but I have seen it work. Also, try the SQC board to see if anyone has extras there.

Big Truck: 00, 3.5, Endeavor, 5-Spd drive line in hand!
Little Truck: 87, 2.6T I/C, MT, LSDs, Tonneau Top
Her Truck: 03, 3.8, 20th Anniv, 65k
Daughter's: 06 Eclipse, Keeping it Mitsu!
FSMs: MitsubishiLinks.com