Roden announced 2 WWI kits recently.
FWD Model B 3-ton ammunition truck & BL 8-inch howitzer Mk. VI with limber
The news:
http://www.roden.eu/HTML/framemodels.htm
More details:
http://www.roden.eu/HTML/713.htm
The US-built truck was produced in large numbers for that period (nearly 18.000 were delivered).
The howitzer saw service from WWI to WWII. Afaik, operators were the UK, USA, Russian Empire/Soviet Union, Finland, France, Canada, Australia & South Africa.
After Strelets announced a great looking set of WWI Turkish infantry a week ago, here are even more good news for the WWI enthusiasts.
Hope that Roden will do a WWII variant of the gun in the future.