At the moment, I hoard my last sheet of GMM stanchions like they're made of gold. As far as I can tell there isn't any good alternative. Soldered wire works for tubular stanchions like on old GE/FM locos, but there's nothing for stamped EMD-style stanchions. For a Geep project I worked on YEARS ago, before I even knew GMM existed, I cut the stanchions off of a regular plastic loco handrail piece, drilled out the tops with a #80 bit, and threaded 0.008" wire through to make the handrails. To say it was tedious would be a spectacular understatement. But we're about there again.