I just got everything put back together and went on my first trail ride in many (way too many) months. Here's the modification I performed. The Blazer is a '90 with the 6.2L diesel, 700r4, 4" lift w/ trimmed fenders, 35x12.50 Goodyear MTR's, front 10-bolt with Eaton posi and 4.10 gears, etc....... 1. Replace the rear 10-bolt (4.10 gears and Tru-Trac) with an '86 1-ton 2WD 14-bolt FF (welded spider gears and shaved diff housing for more clearance). 2. Converted front 10-bolt to 8-lug. 3. Installed 15x10, 8-lug steel rims with 4.25" backspacing. There have been a lot of questions in the past about these type of modifications so I thought I would provide some first-hand feedback. Welded and shaved 14-bolt FF - the welded spider gears really are not that bad on the street (IMHO). The only time it's noticable is during sharp, low-speed turns (such as in a parking lot). You hear a little tire chipping and a little resistance (requires a little more throttle to move), but not that much. I drove almost 500 miles this past weekend with no problems. On the freeway you would never know the diff was welded solid. For the shaved housing, I probably took off around 3/4" off the bottom lip (the bottom is now smooth). I did get hung up in some deep muddy ruts a couple of times and got stuck, but they were deep enough where the front 10-bolt hung up also. A couple of other times I saw where the rear diff dug into the center of the rut but the truck kept going and I really didn't notice any extra resistance. I'm pretty sure getting rid of the huge "boat anchor" lip cast into the bottom of the housing made a difference. I hit the diff on some rocks also, so after cleaning it up I'll see if there is any damage (I don't think there will be any). I also had to cut-off and move the spring and shock mounts (the spring mounts needed moved about an inch or two out towards the wheels on each side, the shock mounts are located on the wrong side of the tube and hung down really low).. No problem, a local welder/friend did this for free. The stock brake lines hooked up to the 14-bolts drums/cylinders with just a little bending of the hard lines. I bought a complete set of 8-lug hub/rotor assemblies from the local junkyard for $50 (they cut them off at the knuckles and even threw in the axle shafts). They were off an '85 or '86 3/4 ton GMC. The spindles and wheel bearings were all the same. I chucked the auto hubs and re-used my Warn premiums, and bought new rotors and calipers (one of my original calipers from frozen up). 15x10, 8-lug rims. These were cheap white spokes from Summit Racing with 4.25" backspacing. They definitely require some grinding of the backing plates (I cut off the bottom sheet metal stone shields) and calipers. Actually, most of the grinding was done to the backing plates with the calipers only requiring a fairly small amount of shaving. Wheels with something like 3.5" of backspacing would definitely require much less grinding, but these turned out pretty well. The biggest clearance problem is that the wheels have a small lip, which only sticks out maybe 1/16", about 2" in from the edge. The rear fit with no contact even with the big 1-ton drums (though there is not much room).