In Box 25 on the CTR, what letter is the correct placement for the US dollar equivalent of Foreign Currency that is brought in to be exchanged ---- letter e "Currency exchange(s)", or letter z "Other" with Foreign Currency noted in the space provided.

Also, if anyone can point me to specific guidance on this specific topic, it would be much appreciated.

The foreign currency would be entered into a 3B or 3C record:

http://bsaefiling.fincen.treas.gov/news/FinCENCTRElectronicFilingRequirements.pdf