In the course of tracing my father's war, I have researched 503d operations on Negros quite a bit. Since they were just north of the 40th Division, I  did learn some about 40th operations.   The 40th had two regimental combat teams (RCT), the 185th and the 160th.  My father's battalion (3d Bn, 503d PRCT)  was opcon to the 185th for two weeks in May 1945.

I have an article which summarizes a trip I took to Negros last year.  The picture at the end of the article shows a muddy road that goes to the foot of Hill 3155, also called Dolan Hill, where part of  the 40th was in action.  It gives you an idea of the terrain your uncle climbed.  The Japanese initially held the high ground you can see at the back of the picture.   I was there just before the sugar cane harvest so the cane obscured much of the battlefield.  However, during the war I'm sure the sugar cane was virtually non existent, and there would have been little natural cover going up this hill.

I did a couple days of research at the National Archive in College Park, Maryland, before my trip.   I copied all the relevant records I could find on my father's battalion, including the complete logs of the 185th RCT of the 40th Division.  However, on Apr 22 there is no reference to a KIA in the 185th report.  They show one WIA.  The records could easily be incomplete though, because that week was the heaviest fighting of the campaign.   There are a couple excerpts of the 185th logs in my article reference above.  They will give you an feeling for what they are like. 

There is a lot of information on the 40th Division at the National Archives.  I only looked for the 185th records, since they affected my father.   You would be able to get a detailed description of the daily movements of the entire 40th Division throughout the campaign.   They kept excellent records.  If your uncle was in the 185th I already have the records.

The 27th ID was in Okinawa during April 1945.  Your uncle's 106th Field Artillery Regiment could have been pulled out and attached to the 40th.  I would think that on Okinawa there would have been  limited requirement for field artillery.  Ships and planes could have done the job there.  The island is very small and  I noticed the 27th ID  had two other artillery regiments, so your uncle's regiment could have been sent to the 40th ID on  Negros.  Or possibly just personnel, but no equipment, were moved from the 27th to the 40th.  I notice that the 185th Regimental Combat Team had been in the 27th ID until 1942, at which time it was transferred to the 40th ID.

Since you live near Maryland, the best way to get solid information on what happened would be to go to the National Archives in Silver Springs.. You can request  information regarding the the 27th and 40th Divisions during 1945.  They have an index which lets you limit what you get.  You should easily be able to find documents that indicate where your uncle's 106th Regiment was at all times.  Even if your uncle was moved into a small unit to Negros, you may be able to find documentation on that.  I found regimental logs for the 40th ID with no problem, and would expect you could find the 27th Division or even the 106th logs.

If there are archives or military museums within New York they may have information also.  I went to an archive in Minnesota to research my ancestor's Civil War unit and found solid records.  I could tell the unit history  had been "enhanced" by the officers, but still give a very nice picture of their experience.

The U.S. Army Center of Military History is a worthwhile website to learn how to research the area. You can also look at the National Archives website. NARA offer research services and can tell you what they have.  The more specific instructions you give them the better.  They charge a lot for copying, I think 50 cents per page, and I don't recommend that, unless you can narrow your request down to a specific document. 

Possibly your uncle is buried in the cemetery in Manila.

Steve Foster
O' Fallon, Illinois