Bolt sleeves big unough to fit the bolts through, stock is 12mm, 1/2" will fit. I think 3/8" pipe will suffice, may need to bore it out to clear a 1/2" bolt. I made a plate for a damaged inner frame rail after the original AllPRo box install failed:
http://www.4crawler.com/4x4/CheapTricks/CrossoverSteering/index.shtml#SteeringBoxReinforcement

and later added a plate to the outside of the frame:

[Linked Image]

Use the box as the template for the plate, shove the box as far forward as you can get it.

r.c.brown@ieee.org
TruckEditor@tlca.org
Project: 4Crawler
4Crawler OffRoad - 4x4Wire discount code