In 1954, the shape of the bellhousing changed where the motor mounts attach. 53 and earlier trucks have vertical mounting points and 54-up mounts are angled about 45 degrees. You would need to change the firewall crossmember to use the later model bellhousing.
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!