I've got a '46 and I replaced the battery tray about 20 years ago. Although I'm sure that there was some system to hold the battery down, I never tracked one down. The battery has just been sitting in the tray for the past 20 odd years and 40,000 miles with nary a problem.
Of course, I'm not involved with the local hill climbers group, nor do I go charging down bumpy dirt roads. I'm just saying that, with reasonable driving, your battery will sit there just fine on its own.
David Bush
