I've removed axles on my '91 chevy truck and my '92 tbird and every time I didn't replace the axle seals they leaked. that is three times with new seals two without. i'd say do it.
one time was putting a used 3.73 differential in replacement of my 3.08 differential and autozone gave me seals for a smaller differential. I still need to fix this.
the last time was on the chevy and seals were not all that old but they leaked onto my brakes. luckily they are semi-metallic pads and cleaned up good. I think organic would have been ruined.
1992 Tbird LX 5.0, 3.73 gears, 1995 Cobra intake, deleted air silencer, 2.5" mandrel bent dual exhaust, SCP shorty headers. Updated four-hole fuel injectors. SK shift kit in AOD. Vogtland 0.9" springs, Tokico and Bilstein shocks.