SR5 4x4 with 266,000 should I replace ball joints ?

Seems like a dumb question but how far will these go?
1998 sr5 x-cab 4x4 2.7 stick
I got it used at 166,000
If they fail in a bad place it could be ugly.
I have no signs or symptoms, tires wear great, no bump steer or rattle
is there a check ?
I asked the guys at the Americas tire to check it when I got new BFGs and they said it seemed fine on the rack

 

Do they have play? If yes replace them...if no then keep driving

 

I.m.o with the high miles and you have put at least 100k on them and who knows when the last time they where changed? and you are kinda worried about them failing I'd just change them. There simple to do and the parts themselves are pretty cheap...about 30-40$ bucks per side. Preventive maintenance and peace of mind can go a long way.