Absolutley. According to Wikipedia, Timken has been making bearings for 109 years, has 27 plants worldwide, employs 25,000 people and are sufficiently concerned about quality that they make their own steel (or used to anyways). They have been an OEM supplier for many years.
They know what they are doing. Most bearings I have used on vehicles (GM and others) and construction equipment all have been Timken or SKF.
I would rather have Timken aftermarket bearings than GM bearings with no name stamped on them.