when looking at a part number for a particular transistor what is the letters at the end for..
ex. 2n5088 and 2n5088TA or TF etc. etc.

 

Typically it is package designation or a temperature grade.

(* jcl *)

 

The datasheet should tell you that information. The 2Nxxxx is registered but IIRC the suffix is up to the manufacturer. In most cases it's used for environmental or packaging or both.