The housing is likely specific to the deck's manufacturer. It's normally possible to remove the old broken lamp and re-use the fixture, but if the material's too fragile at this point, might have to fabricate something similar. No way you'll find a new lamp in that housing, is my bet.
I'd find a lamp (either grain of wheat w/leads, or bare wire terminal lamp) and splice it to the end of that harness, then figure out how to mount it in the original housing.
BTW, usually those things are a rubberized or plastic housing that the lamp is inserted in, but it may have fused into a single part with age. It may even have been cast around the lamp, can't tell from the pics. You may have to destroy the lamp and remove it in pieces to preserve the housing.
John