"With Chinese Military Guard Standing Close By, Ground Crew Of The 14Th Air Force Work On A North American B-25, Preparing It For Another Raid On Enemy Installations."
This is likely B-25D-15, #41-30381, assigned to the 491BS/341BG while the unit was stationed at Chakulia.
1. The standard perspex observation cone is cut, leaving 1/3 of the cone in place (compared to an unmodified cone here).
2. At the top of the cone there is an additional angle piece, serving as an edge/trim, and part of structure to hold on boxy top (not shown), which is not part of the original assembly.
3. The engineer/airman is standing or probably kneeling inside the fuselage, not on the top of the tail plane. This means that the top panel has been already cut out - there was originally no hatch or an openable panel there (compared to an unmodified tail here).
4. A gun sight has been installed.
A ground crew of the 341st Bombardment Group does maintenance to the tail gunner position on a B-25, which appears to have already had a field modification (adding a boxy tail-gunner’s canopy to an earlier B-25 model, which was done to a number of B-25s; see example here, here, and here), possibly in Chakulia. The location of this maintenance appears likely to be Yangkai.
Kneeling under the tail of the aircraft is Lemmon, and the man in the gunner position with cap upturned may be Jim Lane, and the man on the scaffold may be Red Cummings. The names of the GI looking up, and of the Chinese soldiers, are unknown.
(Thanks for the terrific research and information supplied by Yves Marino and Tony Strotman.)