Hello !! I have an original 10 Bolt in my 69' Firebird that I have a few questions.

It is leaking fluid from around the part that attaches to the driveshaft. So I need to replace that Seal.

Should I also replace the other 2 seals that are in the axles ?? If so, does someone sell a seal kit ? How would I replace them ?? I am on a budget so only want to replace if absolutely necessary (is there any possibility the seals are still ok after 40 years ?)
Thanks !!!