I get an almost identical measurement (42 1/4") from a 51 GMC rolling frame with Bendix brakes that I'm parting out- - - - -center to center of the spring bolts. There's a very slight curvature of the tape measure over the banjo housing.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!