How do I know which carrier bearing to get?

[da_raabi]

I picked up a nasty vibration after I did my TH400 rebuild - and it's obvious that its coming from the driveshaft. Looks like I need a new carrier bearing and probably a balance job too.

My problem now is I can't figure out which carrier bearing/center support I need. There seems to be a dozen different sizes and types and I have no idea where to start!

So how do I figure out what I need?

This is on an 86 C30 crew dually.

 

[yevgenievich]

I ran in to similar problem with a 94 crew cab. Picked up all options from a parts store, installed the one that matched and returned the rest. Otherwise have to measure it