Early Ford Transmission noises!! please help!!

hi all

i have a 36 ford trannie with lincoln gears, i which i just rebuild.

yesterday went for the first test drive and everything seems fine other than sometimes when i engine brake, like coming to a stop light in makes a strange ticking sound which stops when i put in the clutch.

not sure if i have given enough info, but anyone got any ideas what it could be?

 

i forgot to say that it is behind a sbc