I'm guessing they are identical?

I found an 01 in great condition and am thinking about swapping my transmission (loaded with INTENSE goodies) into the 01 and vise versa. Then I can sell the 98 and not take a loss.

01 SSEi and your 98 SSEi?

They should be the same. Although your 98 trans should be better than the 01 because it should have been updated with the 03 updates when it was rebuilt.

Yep, my 98 has all new clutches, etc.

My understanding was that they updated valve bodies etc in 03.. No matter..I'm pretty sure you got all the updates.

Do it

won't you need to change the end cover and wiring harness?

What is different about the end cover?

when I bought my used 2000 SSEi trans, I was told it had to come from another 2000 SSEi and it had to have the exact same 3-digit code on it. Mine was CHB.