5th and 11th, 155mm Gun Bn, VAC USMC WWII

I'm searching for info on my Father's Unit, 11th Bn, 155mm Gun Bn, V amphib corps, His name was Corporal Richard H. Maurer, and he saw action on Leyte, He was a Forward observer, I'd like to find out which Battery he was in. I have some records of his Promotion, and a big list of names on it. I want to know the best way to get Muster Rolls and possibly even some Unit Reports, not much has been written about the 5th and 11th and Hq's Bn, on Leyte. But several stories he relayed to me, have since proven to be quite accurate. For instance, he once told me that he was attacked by Jap Paratroopers, I never really believed this, as I thought I knew about WWII and the Japs didnt rely much on Paratroopers. But he was correct, elements of an US Army Artillery Bn, to which the 11th was augmented, were in fact attacked by about 350 of these specially trained shock troopers. Also, another tale he told that never made sense was, He claimed a German Pilot was captured on Leyte, well, pops didn't get ALL the Scuttlebutt on that one, It was a Marine aviator that crashed offshore and swam in and who the Natives thought was a German. So I'm sure that story was bandied about the island and thats how he knew it. There are several more events he told me, and now I believe everything he told me was accurate and how he remembered them. Unfortunately, My Father died in 1994, and I regret at not asking him more questions. He would have loved to see a Forum like this. He was and always will be a Proud Marine. Semper Fi and Thanks for any help
Kevin Maurer
US Army veteran
Desert Storm Era