5. INVENTORIES

Inventory costs include materials, labor and factory overhead. Inventories are stated at the lower of cost or net realizable value, determined on a first-in, first-out basis. Appropriate consideration is given to obsolescence, valuation and other factors in determining net realizable value. Revisions of these estimates could result in the need for adjustments. Inventories, net of reserves, at March 31, 2018 and December 31, 2017 consisted of the following:

	March 31, 2018		December 31, 2017
Chassis	$	8,908	$	7,525
Raw materials		34,144		30,109
Work in process		13,962		13,521
Finished goods		20,639		17,412
	$	77,653	$	68,567