The last generation of NR and SR ders had this revised spring placement. The earliest SRs that I've seen like that were marked Pat 84. All the 85 and later units were unmarked, or possibly marked Pat 11, or Pat 22, and as far as I can tell all of these have the revised body spring. So, short answer is that it is a post 1984 NR that you have.
There are at least two, and I think three, types of body pins. The type you're talking about is the last type. They were removable with a punch, of you drove them from the knurled (non-peened) end. I suppose they were reusable, provided that the knurled-end holes in the upper and lower body did not become oversized.
Tom Dalton Bethlehem, PA USA
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