Normal operation. It is more apparent on some, but not to worry.

 

The 04's SHOULD have the 48RE. The 03 SO's were supposed to have the 47 with the HO's having the 48 but that is not a hard and fast rule.

The shudder the original poster is feeling is NOT a good sign be it a 47 or 48. The TC should lock firmly without a shudder at all times. The shudder, if it is in the TC, means the lockup clutch is slipping.

Unless something was changed on the later 47RE's they were not capapble of handling a quick lockup like the 48's. The TC, line pressures, and flow were not high enough for that. It would not surprise me that a 48RE ECU was matched with a 47RE on the switch over year and that would be a potential issue.

There should be a plate on the trans that indicates what model it is. Thats the only way short of a tear down I know to tell for sure the trans model.