I have two modulation transformers that I'm pretty sure go to a BC-610. 21000 ohm primary, 8000 ohm secondary@250mA, 250Watts. Also says MIL-T-27, grade 1 class A, and B&W part No. 10-900 C. Built by Chicago transformer. Excellent condition, nice potted transformers. $50.00 each plus shipping.
I also have two power supply filter chokes that I'm pretty sure go to a BC 610 as well. Stancor part number 56B013. Some rust, but good overall condition. $20.00 each plus shipping.
MOD Transformers BOTH SOLD