Maybe. A GMT 400 suburban, right?
I recall I read somewhere else the change was made in the middle of the year. I can't remember if 98 or 99. So if the vehicle was made late in that year, it's possible.
But I really don't know. Stick an inspection mirror behind the bell housing and see if you can spot the empty 12 o'clock hole.
This is what my 4L60e looked like after I dropped it from my truck. Note the top hellhousing bolt hole was empty:
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