Why not use newer version (clearance on one side) gimbal bearing in older drive?
 

Not really sure why you couldnt if you werent sure which driveshaft/u joint assembly you had and if you needed the clearance just use the 98-up (or 2000-up depending on what you read) bearing? I have an older drive for sure serial 0F5, and one that is 0Lsomething. The first definitely didnt come with the offset side bearing, but i just pulled out two good shape sealed, offset side bearings from the looks of them.

So why not use Sierra 18-21006 (sealed offseet) on everything and be done with it?