Mechbuilder's Overalls

Mechbuilder's Overalls is a cloth chest piece with some decent attribute boosts and a minor Arcane Resistance. It is one of very few (perhaps the only) chest pieces which require Engineering to wear. It is popular with Engineers for this reason, though more for the novelty than for the bonuses.

Source
Various mobiles of levels 25-31 in Gnomeregan drop this item. Notably, the Holdout Technician, Holdout Warrior, and Mechano-Flamewalker show as the most likely carriers.