Burner information and upgrade questions

[Alejandro Zorrilla]

Hey Ken and fellow bass players!

I have a 5 string Burner from 1992 with serial numbre 92713 AM5

I know it is a 92´ made bass, and assuming it´s your 713th bass made but what is the A M 5?
Maple and 5 string seem logic but the A?

Also Ken do you remember the specs on the built in preamp used for this bass? It´s a bass - treble with pan and volume with push pull. I wonder if there is anywhere I could read about which frecuencies are affected en each band since I´m deciding wether or not to replace the preamp with an Aguilar OBP-2 preamp.

best!

Alejandro