SPG- M109-M109A2/A3, 1/35th, Testor's/Italeri.. OOP, but still on Ebay for about 30-45.00 price-range... There's eveb resin interior sets for both the turret and hull...Ammo canisters, projos, and loose fuzes/fuze-cans (look the same as .50 cal ammo cans, BTW), available from AFV...
Interior detail sets are expensive though, and require opening of gunner's top hatch, and the two turret side-hatches for easiest and most viewing area. When used with the AFV Club M548 Ammo track, it's a REALLY bif display, at least a foot and half long, two would be better... Add the crew's individual fighting positions (read: Foxholes) for width... Add the collimator too... Looks like a "spotting scope", emplaced "backwards"... It function is for aiming the gun on it's left-/right deflection...
M7 Priest 105mm SP Howitzer. Testor's/Italeri... About 30-35.00 on Ebay.. Built the Academy version, and saw no real improvements with it... None, at least, worth the extra 25.00 bucks over the Italeri kit..
M198 155mm Towed Howitzer. Don't know what to tell yas about this kit as I haven't built one, or even bought one.. Too rich for my blood, in other word... Needs a 5-ton truck for a PM...
M102 105mm Towed. 1/35th AAFV Club. About 40.00.. Needs Duece & a half for a Prime Mover, M35A2, also available from AFV Club... Another 40.00 bucks.. Currently, the only truck kit is the Gun Truck, but can be built into the Arty Prime Mover be leaving off the quad-fifty (always can find a use for that somewhere else, as it's a stand-alone kit in itself, almost.)..
M2A1 Towed 105mm.. Italeri, and Dragon... Needs Italeri or Tami Deuce & a half for Prime Mover..
http://www.finescale.com/en/Products%20and%20Reviews/Kit%20Reviews/2009/09/Dragon%201-35%20scale%20M2A1%20105mm%20howitzer.aspx
M101A1, Testor's Italeri pretty much the same as M2A1 105... Main difference i that it's an updated, Vietnam era gun, M35A1 for a Prime Mover (Gas burning, non turbo-charged truck vs the M35A2 multi-fuel deuce...
All 105mm ammo is available either in the kits, both as "loose" projos and in their fibers, or as accessories from AFV.. I used the 5-inch rockets from the Monogram F4U-4 and a few other kits to make complete rounds...
That takes care of the US Army side of the house, as far as what I know about..