I'm really no expert but an equipment trust is not really a lease per se. Railroads normally financed a lot of their equipment purchases through banks.
For instance, if EMD sold 15 locomotives to the New Haven, the NH would arrange for a bank to pay EMD the entire amount and hold title to the locomotives "in trust" for the New Haven. Under the terms of the trust agreement arranged between railroad and bank, the locomotives would be paid off usually over fifteen years in annual payments. At the end of that time the locomotives would be owned by the New Haven.
The plate you have the photo of would be attached to the equipment. If you have or have access to a Moody's Transportation Manual for Investors, for 1954 or around that time, you can probably find out exactly what equipment was covered by that particular trust, No. 1 of 1953.
Less expensive equipment was often paid for by the carrier. Depending on the carrier's financial position I believe some even preferred to pay cash for locomotives. Roads like the New Haven, sad to say, didn't have the financial resources to be able to do this.