Just a heads-up for you: Since you already have the 12v but no 5-spd yet. I'd go with a NV3500 trans instead of the stock Getrag. A quick Google search of Getrag and you'll figure out why pretty fast.
And be sure to check out the "diesel conversion" area of our forum here:
http://67-72chevytrucks.com/vboard/f...play.php?f=240