The guide rod can come loose and you'll lose caster placement of the wheel and steering ability. I've never heard of a guide rod mount failing catastrophically. In the infrequent case there is a catastrophic failure, it's caused by rust, not a worn bushing.

No need to remove the spring if you're not going to replace the forward bushings. You need a come-along to pull the lower control arm forward enough to remove and replace the guide rod mount.

Sixto
87 300D