?'s about 14 bolt semi floater posi

I pulled a posi out of a 1987 3/4 ton 4x4 burb with 14 bolt semi floater rear diff. The diff had 8 bolt axles. The rear had a 3.73 ratio. This posi looks like what I believe is referred to as a gov lock, i.e. it doesn't have any clutch plates that I can see, or at least not as packed as a regular car posi. I can't find much info on truck diffs, but am somewhat familiar with car diffs and what gears fit with which carriers, so I'm wondering:

Can I use this posi in my 92 k2500 14 bolt semi floater diff with 6 bolt axles?
My 92 has 3.42 gears; will the 3.42 crown gear bolt onto the 3.73 gear ratio carrier and be able to mesh properly with the pinion gear once the carrier is shimmed?
Can I use synthetic oil in the dif?

My 92 GM truck manual says that posi and non-posi carriers are interchangeable in 14 bolt SF diffs, but I'm not sure if there are different series carries as there are in cars. Thanks.