There is another option that will allow you to keep the original rearend; a third member from a '55-'62 will bolt right into the original housing. Since you're looking at a non-stock rear suspension (I'm assuming a 3 or 4 link), the pivots will be a non issue. Check out the Parts For Sale section, you may be able to find one there. The common gear is 3.90, but there is a 3.38 available for it. Either will most likely be a better gear than the Nissan, as Japanese trucks tend to be even lower geared that USA truck (I've seen them with 4.55 and lower on 1/2 tons). The driveshaft is a different issue, may have to have it custom made. Ask the local stock car racers where they get their shafts made, that's usually the best places to get one, both in cost and quality.
