Well I'm just thinking...
My '92 as it sits. V6 5 speed, straight & rust free 108K miles.

To put it in perspective:

Upgrades needed to be diesel & worthy:
4D56T - new crate ~ $4,200
Misc items for conversion ~ $1000 - yea it will add up, consider a good Centerforce clutch setup will be about $400 of it.
Install and sort it out figure 20 to 30 hours.
Tires/Wheels ~ $1200
Recover seats in leather - ~$1000 (front 2 and rear bench with fanny heaters).
Rear Locker ~$600 including all new bushings, rotors, seals, lines, calipers etc.
Front LSD, idler, pitman, tie rods, ball joint X4, front bushings, rotors, wheel bearings, calipers, lines, shocks, seals etc ~$1000.

So starting with a clean chassis, $9000 for a good upgrade plus a bunch of labor.

Would / could a '92 be worth ~$12 to ~$14K?