I just picked up a Garret T3 42/46 trim turbo for 40 bucks, but the internal wastegate is missing. Do I have to find an internal wastegate for it or can I use a 38mm Deltagate wastegate with this?

 

Are you referring to the wg actuator or the housing with the flapper? If you have the flapper housing, you can use any wg actuator you want, but you have to get creative when mounting it. Otherwise, you'll need a blockoff plate and an external.

 

38mm deltagate is a little on the big size for a .42.48