The bearings for an ultima should be the same. if I remember correctly:
6 - 5mmx10mm (rear hubs and top shaft in the gearbox)
4 - 4mmx8mm (front wheels)
2 - 4mmx8mm flanged (for the large gear outside of the gearbox)
2 - 8mmx14mm (not sure of the size...for the diff)
the only parts that are different from the ultima are:
Chassis - ultima has an aluminum rail or graphite plate. outrage is abs plastic...so don't get motor spray on it.
Shock Towers - ultima has either aluminum or fiberglass...outrage has flexible plastic
Shocks - ultima has either aluminum (red, gold platinum) or kelron plastic (ultima 2) in different lengths. The plastic shocks on the outrage are different. If they start to leak, you should replace the black O-rings with the orange O-rings (look at an associated rebuild kit)
Rear axles - I don't remember if the outrage uses a pressure fit aluminum hex like the ultima or a pin in the axle that holds a plastic hex.
Wheels - same size as yours, but different styles and colors.
Top plate - ultima has plastic, fiberglass while the outrage only has 2 piece plastic plates
Tie rods - ultima uses a ball end and a rod or turnbuckle. the outrage has a plastic bar
Body
As for the motor, check to see that there isn't a small screw or something causing it to bind. Can it be turned by hand?...is it so dirty that there is no electrical contact between the comm and the brushes?
As for upgrades...you'll eventually need new tires. The 1.9 fronts and 2.0 rears are very expensive and hard to find. If your rear axles use a pin to hold the hex in place, then you can use the 2.15 traxxas wheels. The fronts require a 5x11 bearing, but you can buy bearing adapters from hpi to fit the 4x8 bearings. The rears use the pin but no hex. You'll then be able to use the modern tires for your cars.
http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXJJ72&P=7
http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXJJ73&P=7
http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXN055&P=7
Good luck...and post your progress.
Regards,
Roger