Motorola bridge rectifier model MDA 972-4. These are rated at 300 volt and 16 amp. Peak forward recurrent is 60 amps with a single cycle rated at 250 amps. (built for surge protection – starting a DC motor?) Probably need to bolt to a steel or aluminum plate with silicone grease – each unit is 7 inches long. Outer two posts are marked Yellow — inner two marked black and red
New – 5 available $1.00 each.
Note Surplus Sales has these on their website at $25 each.