I happened to come across the MACR for Lt. Mahannah and the others on "footnote.com" today. It's #16296. There's no plane serial # listed on it -- it just says "362". It says they crashed on Formosa during a combat mission but doesn't state the cause. There's a 6th crew member in addition to the 5 you listed: Sgt Joseph G. Bratton.
I was looking up Lt. Tyll when I found the MACR. On the veteran's gravesite database, it's says he died 4/12/45 but the MACR says April 2nd.
If you ever find the plane's serial number, I'd appreciate it if you 'd pass it along to me....Thanks and good luck! (If there's any more info you'd like from the MACR, just let me know)