NOS Vintage Military Peerless / Altec 2" Step-down Transformer #8991 (also has TF4SY01YY) dated 1961, in mint condition, untested, with original box & paper.  This is an aircraft transformer made for a 400 Hz power supply. You can not run it on 120V 60 Hz.  Sold as is.  See photos for detailsSold as is, see photos for further details.  Buyer pays actual shipping primarily by USPS based on weight, package size and destination as calculated through eBay.  Seller reserves the right to substitute a comparable shipping service such as FedEx or UPS to meet the calculated cost.  Will combine shipping at buyers request for total/invoice prior to paying.