Previous owner claimed this was a Shadow Excel, but the guys at Shadow confirmed it's not theirs. I come from the land of Ultramax and Slack so I just don't know enough other brands to figure this out. No markings other than the number "575" stamped on the lower steering post tab. It has caster blocks with heims on the top and bottom of the kingpins. Tabs for the front nerf mounts. No other major details to help identification other than the general design/layout of the tubing/tabs/posts/mounts. Link to pictures on Twitter (public).
https://twitter.com/byski182/status/651091993544814593
https://twitter.com/byski182/status/651091993544814593