Thanks JCL, I checked the fluid before I did the EGS upgrade. The level was good and it looked clean. Definitely not burnt.

It is nice to hear that you have a more positive opinion of this transmission. The research I have done paints a more dreary picture. For example:

"You may have seen my post on stripping down a broken 5-speed GM 5L40-E automatic transmission and it is clear from the comments on this and other L322 forums that this model ... has an unenviable reputation for failure usually between 80,000 & 100,000 miles."
‘Sonnaxification’ of GM 5L40-E valve bodies

When you say you would look at the valve body, what would you do? Are you suggesting a more modest repair? I was thinking that the bill for any type of valve body work would be close to $1000 (the cost of a sonnaxified unit).