UPDATE 1-GM to sell medium-duty truck unit to Navistar--WSJ

(Adds company comments, details)

NEW YORK, Dec 19 (Reuters) - General Motors Corp GM.N will sell its profitable medium-duty truck unit to Navistar International Corp NAVZ.PK, The Wall Street Journal Online reported on Wednesday.

An announcement is expected on Thursday, the Journal reported, citing people familiar with the agreement.

The report did not include terms of the sale.

Navistar spokesman Roy Wiley said that while the truck and engine maker was "very excited" at the prospect of buying GM's medium-duty truck unit, he could not confirm that an announcement would be made on Thursday.

GM, which did not immediately return calls seeking comment, sells the medium-duty trucks under the nameplates Kodiak, TopKick and Isuzu T-Series. It made 59,000 medium-duty trucks in 2006, about 12 percent of the market. (Reporting by Nick Zieminski and Aarthi Sivaraman; Editing by Gary Hill)