This is a new axles thread but why not the reboot from YouTube. It's probably cheaper than $49 per axle and looks simple:
http://fr.youtube.com/watch?v=F17tFS6ofzU&feature=related

By the way... Any way to save this video to HD? I'm not too YouTube savvy.

Those two models should use the same axles. The diff cover does not use a gasket. Clean the surfaces well and use a thin coating of silicone sealer. If you have the time, let it harden for 24 hours before adding a little over 1 quart of 90 weight oil.

You will want to have a pair of diff side seals so you can replace the old ones when you are ready to put in the new axles.

When disassembling, do not drain the diff until you have first removed the filler plug (just in case). If it is stuck, using a little heat on the cover around the fill plug sometimes helps. If all else fails, you will be removing the cover anyway so you will be able to operate on it on a workbench.

There are a couple of nice DIY posts on the forum covering axle R&R.

Jeremy

I had a set of the GSP axles in an 83 300DT about a month ago. So far so good,... no whining or road noise.

I called Advance last week trying to get another set to do another 83 300DT and they were unable to get them at the present time. They apparently called the distributor/warehouse,.. and were told that they were out of stock and they didn't know when they would get some in. Advance priced the axles, if they could get them, at $68 each.

A possible benefit; I saw in one of the service manual pdf files, something on a noise or vibration dampner that mounted on the differential side of the inside CV joint. These new GSP axles are stubbed out thru the differential with a cast iron flange plate about where that dampner would have been. In other words these new axles may be inherently more quiet,.. may just not last as long.