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.