Should I replace balljoints?

[ReconDaddy]

I am new to the site and green to turning wrenches. I bought a 72 K10 LWB last Thanksgiving and have slowly been replacing little things here and there working up my confidence to tackle bigger projects. Today I decided to replace the inner axle seals, replace U-joints on drive shafts, and replace/repack wheel bearings and seals. With the amount of grit and grim inside the drive shaft housing and amount surface rust on the outside I thought I would replace the ball joints while everything was torn down to this point. I do know this truck was only used during hunting season and sat the rest of the year for the last 5 years, same owner since 1977. I can't see any signs of the balljoints being bad and am wondering if its would be a waste of time replacing them? If it's not a waste of time I have more questions, if it is I should have it back together tomorrow. Thank you in advance for any advice.