Joe, I have a SM420 that I pulled out of my 41. It has the mounting bracket for the brake, but I don't have any of the other hardware for the brake. You're welcome to it if it helps you.

I also have a 5 speed that came out of a 59 2 ton truck, 2 spd. axle. That will probably fit, but I'm checking to see if it has the brake on it.

~ Victor
1941 3/4-Ton Pickup (in process). Read about it in the DITY Gallery
1955 Grumman Kurbside "Doughboy" 235/3 on tree w/ OD
1957 3100 - moved on
1959 C4500 Short Bus "Magic Bus" - moved on
1959 G3800 1 Ton Dually "Chief" - moved on
1958 C4400 Viking "Thor" ~ moved on to fellow Bolter