AFV Club makes a real nice M548. Italeri (also boxed by Revell of Germany and Testors) makes the entire range of M109s from the M109, M109G, M109A1/2, M109A3, M109A4/5 and M109A6. The Paladin is boxed by both RoG and Italeri and are the same kit with different decals.
The Revell of Germany M109A3 is a German specific version with German Diehl tracks.
AFV Club also makes the M102 105mm howitzer, real nice kit. I've not seen an M198 or M119 in 1/35 scale injection plastic. The old 8" M110s are floating around in RoG and Italeri boxes as well.