jeff-
rb's obsolete sells a kit to adapt the vega box to your truck, but it's very $$$. i may switch over to the vega box on my '31, as it's supposed to have much less bump-steer than the side-steer. if i make the switch, i plan to buy the vega box off ebay, fab my mounting bracket, and get all the steering rods from speedway.
if you're looking for a drop axle, MAS and RB's both offer tube axles with up to 6" of drop (remember that your stock axle probably has about 2" of drop). the axles use 42-28 f**d or 49-54 chev car spindles. 5 and 6 lug disc brake kits are available for both, as well as all the steering arms, etc that you'd need to mate it to the vega box.
ed
