Yes, AFV Club makes an M102 howitzer as used by the US Army later in the war. It can be built as either a Vietnam version or a more modern version, 1980s/'90s - as shown on the box top.
AFV Club, Dragon, and Italeri make an M101A1 as used by the USMC and the Army early in the war. AFV Club's is the best out of the three.
Dragon's withe late WWII or Korean War crew (not good for Vietnam).
Italeri made one a long time ago too. It is not as good as the two above and has a WWII crew.
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