Dave, here are a couple pictures of the ebrake in my '41. The spring was a bugger to get back in correctly. The small rod on mine is fairly straight. Seems like the bolt that attaches the brake to the transmission was about 3/8, but it may have been 5/16. I just can't remember for sure. I do remember it was larger than I would have thought. Are there threads inside your 1/2" hole?
http://i950.photobucket.com/albums/ad342/summerfi/ebrake1.jpg
http://i950.photobucket.com/albums/ad342/summerfi/ebrake2.jpg



My toys:
'41 Chevy Model AL 3/4 Ton
'40 Chevy Model KD 3/4 Ton
Hinomoto 209N Tractor/Backhoe
Norwood LM2000 Sawmill
PJ 16' Trailer
and a Brand New Shop!
Be what you is, not what you ain't, 'cause when you is what you ain't, then you ain't what you is.