transmission ID codes

[tilliepeople]

I am looking to replace the tranny in my 2001 expedition .
When I look up different trannys I notice an ID code (1L3P-BA ,1L3P-BB ... ) .
Is there a difference ? How to I find out which one I need ?
Thank You
Bill

 

[tilliepeople]

Crawled underneath and found the tag.
Found a used trans at a reasonable price and ordered it .
Should be back on the road in a few days