Although I already had a US Armoured infantry battalion (made with Airfix half tracks) I found a scenario that need two battalions, so I acquired more of the Plastic Soldier Company version when I bought their M5 Stuarts. I wanted to create some variety and perusing my books and plans I realised I could convert the M3 into an M2 especially for use as a gun tow.
A pair of M2s either side of an M2A1, which has a pulpit as the main visible difference. I'll use the later as a 57mm gun tow and the other pair for the 3" AT guns. Most the pictures I could find showed them covered with stowage at the back and note the shortened mine racks.
More M3s personalised with assorted stowage
For those interested in the M2 conversion, here's a work in progress picture showing the main changes.
The hull sides are reduced by 3mm at the rear end carefully leaving the triangle behind the tracks. The interior is similarly reduced but by separating the rear compartment. The rear compartment is then reversed and refitted. At the rear the panel has to be adjusted to align with the new upper hull position, but with the lower third cut to fit the triangles on either sides and the centre stepped in to match the upper hull. I didn't bother removing the rear door as it would be hidden by stowage. The hull sides have the existing central panel line filled and a new one added ahead of the cut down mine racks. Finally two large stowage boxes from plasticard were added to the interior.