All About Pocket Knives

This is a small thing but bugging me. I got a basket case Buck 703, pre 86, two of three blades totally missing, really trashed and worn out. As I was playing with it, a bolster just fell off. So I was wondering - on the all-stainless models - how were the bolsters attached? I see no sign of solder/braze, no extra pins, nothing.

I have had a few of the 300 series apart and back together and on those the stainless steel liners and bolsters are spot welded together.