The cleaning gear carried in the butt varied according to the time frame, AND according to what the Quartermaster had in stock.
The correct bayonet for a very early war M1 would be a 16" version, likely with the black bakelite handles.
From around 1942 on, it would be a 10" model, either a earlier version cut off to 10" or a Model M1 bayonet made with a 10" blade.
The "official" bayonet for most of the war was the Model M1 10" bayonet. (The bayonet was called the Model M1).
For the onboard cleaning gear, the top hole would usually have a canvas tube containing:
4 sections of the cleaning rod.
A loop tip and a brush, joined together by a short section of clear tubing.
A tiny plastic "jar" with grease. During the war it was Lubriplate, a white lithium grease. Later it was Plasti-lube a brown grease.
A couple of patches to fill any excess space.
The bottom hole storage varied quite a bit, depending on what was available.
"Standard would be a long nickel plated brass tube, containing:
The front of the tube is full of oil.
The rear would have either a rolled up thong and bore brush, OR more likely, a M10 Cleaning rod handle.
The handle would be wrapped in a patch, and more patches would be on the end of the handle to prevent rattling inside the tube.
Any excess space in the hole would be filled with more patches to prevent the tube from rattling.
Later in the war, the plated brass tube was replaced with a amber colored long plastic tube.
In some cases, instead of the tube, the M3 or M3A1 Combination tool would be carried in the lower hole.
There are many sources of buttstock cleaning gear, and the tiny grease pots or jars can be bought in cases of 144, cheap.
After Korea, a chamber cleaning tool was introduced which has a plastic "ratchet" mounted behind the brush, and a short amber colored oil and grease tube used on both the M1 and the M14 was used. This IS NOT "correct" for WWII gear.
Here's a link to the CMP's pages on M1 accessories. This shows the various gear and some different ways it could be carried:
www.civilianmarksmanship.com/accessories.html