Yes -- they changed this last year I believe. All flights in the US-50 are now eligible for upgrades including D1 flights but those flights were previously excluded.

Lists tend to be insane on JFKLAX and JFKSFO so I would plan to sit in C+ and be pleasantly surprised if you get the upgrade. Plus Thursday is a busy travel day for business travelers so I would expect a number of DMs on that flight flying back to LAX after the week in NYC and last minute paid J isn't out of the question.

Last week on a Sunday afternoon JFKSFO I ended up #12 for zero seats (with none clearing at the gate) as a PM on a corporate Q fare