Auctally, Credit does to someone else doing the mod wish I knew who it was. I purchased this from Wayne he purchased it from the person who modified the unit.
Originally, It had a CoinMaster 5900/Di Professional Series board. Manual ground balance model, Although it operated great this particular model didn't have that extra punch later blue box models had.
Recently, A friend gave me a blue box CoinMaster 6000/Di Professional Series with Auto/Track. Had some issues, fixed the problems and its great has that extra depth I needed. So I swapped boards and lower control housing, since both boards are similar was able to retain upper housing connected to handle and just drilled out a hole for the Auto/Track toggle.
Very impressed with this older blue box 6000/Di Auto/Trac Series, has extra depth using a sensitivity control. The Fisher DD coil is a perfect fit for this older model, kHz are very close don't notice any difference's with ID.
Thanks and take care,
Paul