6k to fix unless you really love that particular d2 it's a nope its time to move on unless you have all ready spent $$$$ on it doing gearbox or a lot of accessory's as your spending what its worth running to make it running again.
if it has a lot of accessory's on it look at getting anther d2a to transfer it all over to for what your doing anything under 250k or has had a gearbox rebuild would be fine id guess.

if you havent sunk a heap of coin into it your options are wide open ether a d2a or a d3 petrol or l322 v8 (stay away from the td6 pre zf6 speed as the gearbox is a pile a crap that's underrated for the job and about 8k to replace it makes the td5 auto look like the worlds strongest gearbox in comparison)
but for what your doing honestly id be looking something japanese