Axle and brake questions

[red250]

Hi all, new to the site. I purchased a '87 f250 6.9. I have some questions about the brake system and axle set ups. The truck has some other axle than stock and RABS is not hooked up. Axle on the truck has reverse thread on drivers side and a 2 on the horizontal gusset on pass side. What axle is this? I am searching out the information regarding going back to a Sterling axle and converting to a disc set up (looking at these http://www.ruffstuffspecialties.com/catalog/STER-DISC.html) or van axles if they will work with same bolt pattern. How do disc work with RABS? and what are different folks oppinions of keeping or bypassing rabs with discs? Wrecking yard has some 2nd gen sterling 10.5 for $500. Looking for information and any advice.

here's link to pics of axle on truck. http://www.flickr.com/photos/79056933@N07/

Thanks in advance to all.

 

[red250]

So I did more research from the gentleman I purchased the truck from, Thad (from his old posts.) The Truck has a Dana 70HD under it now. So now just have questions on the RABS. Whether to keep with discs or junk'em. I am going to bypass for now. Some of the issues we resolved on the crap work were bad front calipers, the rear brakes needed to be completly rebuilt due to bad shoes, hardwear and cylinders, and whoever did the last axle seal job tore out the seals and left the metal ring of the old seal on the the axle, so this caused the new seals to leak and then diff fluid into the brakes. So I have fresh seals and new brakes on the D70HD and wanna get rid of it. We also redid return lines and I am getting 18mpg on the highway right now. I plan on getting new exhaust and the axle in the near future.